President Barack Obama said Friday that he encouraged Prime Minister Benjamin Netanyahu to minimize civilian deaths in Israel’s ground push into Hamas-ruled Gaza, while letting him know that the US supports Israel’s right to self defense.

“No nation should accept rockets being fired into its borders,” Obama told reporters at the White House. The US president said he spoke by phone with Netanyahu earlier in the day, over the sounds of sirens going off in the background in Tel Aviv, and told him Secretary of State John Kerry is prepared to travel to the region.

“I also made clear that the United States and our friends and allies are deeply concerned about the risks of further escalation and the loss of more innocent life,” Obama said. “And that’s why we’ve indicated although we support military efforts by the Israelis to make sure that rockets are not being fired into their territory, we also have said that our understanding is the current military ground operations are designed to deal with the tunnels.”

According to Netanyahu’s office, an air raid siren sounded mid-conversation with the president as Tel Aviv came under fire from the Gaza Strip. Netanyahu told Obama that “this is the reality for millions of Israelis in recent days,” according to a statement from the Prime Minister’s Office.

Netanyahu also told Obama that Hamas is using civilians as human shields in Gaza, as was shown Thursday when 20 rockets were found in a school run by UNRWA.

“Therefore Hamas is responsible if residents of Gaza are being hit,” the prime minister told the president.

He thanked Obama for America’s support of Israel’s right to defend itself and for helping develop the Iron Dome missile defense system.

Israel’s ground offensive followed a 10-day campaign of more than 2,000 airstrikes that had failed to halt relentless Hamas rocket fire on Israeli cities. Israel stepped up its campaign after the Islamic terror group refused to accept an Egyptian truce offer.

IDF Artillery Corps seen firing shells to Gaza, near the border in Southern Israel on July 18, 2014, after Israeli forces began a ground invasion in an escalation of the operation as it entered its 11th day. (Photo credit: Hadas Parush/Flash90)

IDF Artillery Corps seen firing shells to Gaza, near the border in Southern Israel on July 18, 2014, after Israeli forces began a ground invasion in an escalation of the operation as it entered its 11th day. (Photo credit: Hadas Parush/Flash90)

On Thursday, Kerry told Netanyahu that the US strongly supports Israel’s right to defend itself against threats posed by the Gaza tunnels dug into Israel. Kerry urged Israel to limit its ground operation to a precision offensive against the tunnels, the State Department said in a statement.

“The secretary reaffirmed [the US's] strong support for Israel’s right to defend itself against terrorist threats emanating from tunnels into Israel and expressed our view that this should be a precise operation to target tunnels, as described in a statement from the Israeli Defense Forces,” the statement read.

During a phone call with Kerry, Netanyahu emphasized the attempted terrorist attack that was thwarted near Kibbutz Sufa on Thursday morning, and stated what the State Department described as “the imminent threat to Israeli civilians posed by Hamas tunnels from the Gaza Strip.”

Netanyahu discussed with Kerry his decision to launch a ground operation to target the threat of further terrorist infiltration through tunnels into Israel.

US Secretary of State John Kerry arrives in front of a hotel where closed-door nuclear talks on Iran take place in Vienna, Austria, Monday, July 14, 2014. (photo credit: AP Photo/Ronald Zak)

US Secretary of State John Kerry arrives in front of a hotel where closed-door nuclear talks on Iran take place in Vienna, Austria, Monday, July 14, 2014. (photo credit: AP Photo/Ronald Zak)

According to State Department officials, in addition to offering support for the operation against Hamas’s underground networks, Kerry “emphasized the need to avoid further escalation and to restore the 2012 ceasefire as soon as possible.”

The statement came a day after State Department officials were pressed as to whether the US had only cool support for the Egyptian proposal, which was reportedly brokered with the help of Quartet representative and former British prime minister Tony Blair.

On Tuesday, Israel agreed to abide by the Egyptian proposal for a ceasefire, but Hamas refused, continuing to launch rockets at Israeli cities.

In his conversation with Netanyahu, Kerry also reiterated US concern about the safety and security of civilians on both sides and the importance of doing everything possible to prevent civilian casualties.

Kerry’s comments followed a strongly-worded statement issued by State Department Spokesperson Jen Psaki casting doubt as to whether Israel was really taking all steps possible to avoid civilian casualties.

After two separate incidents of Gazan children being killed were reported in as many days, Psaki said that the State Department was “increasingly concerned about the safety and security of civilians on both sides” and said that the US was “asking for a redoubling of efforts moving forward to prevent civilian casualties given the events of the past couple days.”

Psaki told reporters that Kerry had addressed the issue in a call with Netanyahu earlier in the week. “We believe there is more that can be done” to protect civilians, Psaki said.

US State Department Spokeswoman Jen Psaki. (screen capture: YouTube)

US State Department Spokeswoman Jen Psaki. (screen capture: YouTube)

Expanding on her reaction to Wednesday’s killing of four Gazan children playing by the city’s fishing pier, Psaki described the US as “heartbroken” by reports of children’s deaths, and that – regarding the specific incident Wednesday – “the reports were horrifying, the photos were horrifying and the video was horrifying.”

Psaki said State Department officials, including Kerry, “were heartened to see the statement by President Shimon Peres in which he spoke to the deaths of these children” but underscored the fact that they did not consider Peres’s statement to be a condemnation of the children’s deaths.