US President Barack Obama on Thursday told Prime Minister Benjamin Netanyahu he was worried fierce fighting with Hamas in Gaza could escalate, and offered US help to broker a ceasefire.

“The president expressed concern about the risk of further escalation and emphasized the need for all sides to do everything they can to protect the lives of civilians and restore calm,” the White House said in a statement.

“The United States remains prepared to facilitate a cessation of hostilities, including a return to the November 2012 ceasefire agreement.”

The 2012 deal, brokered by former secretary of state Hillary Clinton and Egypt, ended eight days of Israeli airstrikes on Hamas targets in a previous showdown.

The White House statement said that Obama told Netanyahu that he understood Israel had a right to defend itself and that he condemned rocket attacks by Hamas and other militant groups launched from Gaza.

Obama expressed sympathy for the deaths of three Israeli teenagers in the West Bank that triggered new tensions between the Jewish state and Palestinians and praised Israel for swiftly making arrests in the case of a Palestinian youth apparently killed by israeli Jews in reprisal for the incident.

Obama also expressed concern over the case of a Palestinian-American teenager allegedly beaten in police custody.

The two leaders also discussed the effort to conclude a deal on curtailing Iran’s nuclear program by an approaching July 20 deadline. Netanyahu has previously expressed deep skepticism of the US approach toward Iran.

Also Thursday, the US State Department put the blame for the new violence squarely on Hamas and its rocket attacks on Israeli cities.

“I would remind [who] is at fault here, and that is Hamas and the indiscriminate attacks that they have launched against Israel,” State Department spokeswoman Jen Psaki said.

“While the Israelis have taken steps to try to prevent civilian casualties by warning – providing warning in advance, that is not what, of course, Hamas is doing, and they have continued their indiscriminate attacks against – including civilian areas in Israel,” she said during a press briefing.

Psaki added that “no country should have to live under the constant threat of indiscriminate violence against innocent civilians.”

She said that the US was “reaching out to countries in the region including Qatar, including Egypt” to try to mediate a ceasefire.

“Any country in the region that can play a role in bringing an end to the rocket fire from Hamas we’re certainly going to be engaged with,” said Psaki, noting the difference in relationships between the previous Egyptian government of ousted Islamist president Mohammed Morsi and the current one of Abdel Fattah el-Sissi.

Obama and Netanyahu spoke after the Israeli prime minister had spoken to a host of other world leaders after the launch of Operation Protective Edge, all of whom reiterated Israel’s right to defend itself against rocket attacks from Gaza.

Israeli Prime Minister Benjamin Netanyahu meets British Prime Minister David Cameron at Netanyahu's office in Jerusalem on Wednesday, March 12, 2014. (Photo by Amit Shabi/POOL/Flash90)

Israeli Prime Minister Benjamin Netanyahu meets British Prime Minister David Cameron at Netanyahu’s office in Jerusalem on Wednesday, March 12, 2014. (Photo by Amit Shabi/POOL/Flash90)

Netanyahu held phone conversations with UN Secretary-General Ban Ki-Moon, British Prime Minister David Cameron, German Chancellor Angela Merkel, French President Francois Hollande, and Canadian Prime Minister Stephen Harper, officials said Thursday.

Netanyahu also spoke to US Secretary of State John Kerry.

In Netanyahu’s conversations with world leaders, which were often but not always initiated by Jerusalem, the international community condemned Gaza rockets attacks and asserted Israel’s right to defend itself.

Cameron, for instance, “strongly condemned the appalling attacks being carried out by Hamas against Israeli civilians.” He assured Netanyahu of London’s “staunch support for Israel in the face of such attacks, and underlined Israel’s right to defend itself from them,” according to a statement his office released.

Canada’s Harper “reiterated Canada’s steadfast support for Israel and its right to defend itself against these terror attacks,” his official website states. He agreed with Netanyahu that “Hamas must end its targeted attacks on Israeli citizens.”

On Wednesday, Ottawa’s Foreign Minister John Baird tweeted messages of support for Israel adjacent to calls on the Palestinian government to act to end the rocket fire.

His ambassador in Israel, Vivian Bercovici, has been retweeting his messages and authored supportive tweets herself.

Australia’s ambassador in Tel Aviv, Dave Sharma, has been very active on Twitter, posting condemnations of rocket attacks on Israel and photos of his embassy staff in a shelter after missile attacks.

Dan Shapiro, the American ambassador to Israel, has retweeted posts about Iron Dome, the US-funded missile defense system, as well as an excerpt from a speech Gordon gave Tuesday in Tel Aviv.

On Thursday, Foreign Minister Avigdor Liberman sent a letter to his counterparts in all countries with which Israel has diplomatic relations, saying the government’s objective for launching Operation Protective Edge is to guarantee Israelis “a life without constant threat” and that, while hoping to avoid an escalation, the government will do whatever it takes to achieve this goal.

“Over the past three weeks, the Hamas terror organization has escalated its attack on Israeli civilians, launching nearly 300 rockets at our cities – including Jerusalem, Tel Aviv, and other major metropolitan areas — putting millions of Israeli lives at risk,” Liberman wrote. “Families have been forced into shelters, summer camps for children closed, and all normal daily activities have been impacted. This is unacceptable.”

Jerusalem showed “great restraint” before launching the operation, the foreign minister continued, asserting that the government was eager to restore calm without a major military campaign. “However, Israel’s repeated efforts to achieve calm were met with increased rocket fire by what is becoming a Hamas terrorist state.”

Israel was forced to launch “an operation of self-defense” whose objective is to secure for Israel’s civilian population “a life without constant threat,” he wrote. “Although we are not interested in escalation, we will do whatever is necessary to defend our citizens.”

Foreign Minister Avigdor Liberman speaks with the press before entering the weekly cabinet meeting on Sunday, June 1, 2014. (photo credit: Marc Israel Sellem/POOL/Flash 90)

Foreign Minister Avigdor Liberman speaks with the press before entering the weekly cabinet meeting on Sunday, June 1, 2014. (photo credit: Marc Israel Sellem/POOL/Flash 90)

He described Hamas as an internationally recognized terrorist organizations that aims to establish an “Islamist state characterized by human rights violations, violent repression of minorities, women, and non-Muslims.” The group uses Palestinian civilians as human shields, which is a war crime, and therefore “bears full responsibility for any harm that comes to Israeli and Palestinian civilians alike,” Liberman wrote.

“Israel is operating with utmost care to avoid civilian casualties. We are focusing on targeting Hamas and other terrorist organizations, their operatives and infrastructure. Israel is giving repeated warnings to civilians to vacate areas they are about to target, using pinpoint technologies to hit only the targeted infrastructure.”

The foreign minister demands that the Palestinian Authority dismantle the Hamas-backed unity government and calls on world leaders to condemn the ongoing rocket fire from Gaza to Israel. “Finally, the international community should continue to demonstrate understanding for Israel to exercise its legitimate right to self-defense,” he concludes his letter.

Liberman was scheduled to brief foreign ambassadors stationed in Israel about the situation Thursday afternoon.