Iranian Foreign Minister Mohammad Javad Zarif fired back at Prime Minister Benjamin Netanyahu on Tuesday, accusing him of lying by cautioning the world against Tehran’s recent outreach to the West.

“We have seen nothing from Netanyahu but lies and actions to deceive and scare,” said Zarif in an interview with Iranian television, the AFP news agency reported Monday, “and international public opinion will not let these lies go unanswered.”

“For 22 years, the Zionist regime has been lying by repeating endlessly that Iran will have the atomic bomb in six months,” Zarif added.

A short while later, Zarif sent out a series of tweets criticizing US President Barack Obama and calling on him to keep firm to his moves toward detente with Iran.

“President Obama needs consistency to promote mutual confidence,” Zarif wrote. ”Flip-flop destroys trust and undermines US credibility.”

Zarif made his comments from the United Nations in New York, where Netanyahu was scheduled to speak later Tuesday. The prime minister was expected to push for continued sanctions on Iran, arguing that despite the new tone coming out of Tehran, there have been no substantive changes in the nuclear program and that it was financial penalties that brought Tehran to the negotiating table.

“I will say the truth,” Netanyahu told reporters on the plane before taking off for the US. “In the face of the sweet talk and the smiles one needs to tell the truth. Only the truth, today, is vital to the security of the world, and of course essential to the security of our country.”

Israel is concerned over the recent thaw in Western-Iranian ties that developed at a breakneck pace over the past two weeks, culminating Friday in a phone call between the American and Iranian presidents.

Netanyahu met Obama at the White House on Monday, and was to be the final world leader to address this year’s General Assembly.

In Iran, leaders responded to the Obama-Netanyahu meeting by calling on the US to change its approach toward Tehran.

“We still expect that the US officials to deal with the Islamic Republic of Iran realistically and treat the Iranian nation respectfully,”  Iranian Foreign Ministry Spokeswoman Marziyeh Afkham said, according to Iran’s Tasnim news agency. “The actual behavior of this country’s officials towards our nuclear activities are the main yardstick for the Islamic Republic; the US government now faces a test to demonstrate it sticks to its new stances regarding Iran.”

In an interview with ABC Sunday, the Western-educated Zarif said that Iran would open its nuclear facilities to international inspectors as part of broad negotiations with the US that could eventually restore diplomatic relations between the adversaries. Those talks would have the backing of the nation’s supreme leader, he said.

Iran’s nuclear ambitions have isolated its people from the rest of the world and led to painful economic penalties. Iran’s Supreme Leader Ayatollah Ali Khamenei has declared the use of nuclear weapons against Islamic law yet has maintained his nation has the right to develop its uranium enrichment program.

But Khamenei, who is the nation’s ultimate decision-maker, also has given his approval for elected leaders in his country to engage the West over the nuclear program, Zarif said.

In an interview with Al-Monitor Tuesday, Zarif said the US must take steps to ease the sanctions for Iran to make concessions on its nuclear program.

He also indicated that Iran is prepared to help secure Syria’s chemical weapons stockpile in upcoming talks in Switzerland. “Iran is prepared to participate in Geneva II,” he said. “We are not begging to be invited. If they ask us to go, we will go, without any conditions, and we do not accept any conditions.”

Times of Israel staff and Associated Press contributed to this report.