Israeli Prime Minister Benjamin Netanyahu appealed to the world community not to be fooled by the new Iranian president's conciliatory words, using a U.N. address to decry him as a "wolf in sheep's clothing."

Netanyahu, speaking to the U.N. General Assembly session on Tuesday in New York, sought to counter the positive reviews Iranian President Hassan Rouhani got over his debut at the international gathering. As the U.S. reaches out anew to Iran under its new leadership, the Israeli prime minister suggested Hassan Rouhani is no better than his predecessor, Mahmoud Ahmadinejad.

"Rouhani didn't sound like Ahmadinejad, but when it comes to Iran's nuclear weapons program, the only difference between them is this: Ahmadinejad was the wolf in wolf's clothing. Rouhani is a wolf in sheep's clothing," Netanyahu said. "A wolf who thinks he can pull the wool over the eyes of the international community."

Netanyahu spoke after meeting in person with President Obama on Monday in Washington.

Netanyahu is wary amid efforts to re-launch diplomatic talks between the U.S. and Iran, and following a historic phone call on Friday between Obama and Rouhani. The Obama-Rouhani phone call was the first between an American and Iranian president since the Iranian revolution of 1979, which sent U.S.-Iranian relations into a deep freeze.

More On This...

Western officials saw Rouhani's remarks before the U.N. General Assembly last week as conciliatory in tone, and Secretary of State John Kerry has begun working with other diplomats to potentially re-launch talks over Iran's nuclear program.

But Netanyahu used his address to revisit Iran's bloody history in the wake of the 1979 revolution, and Rouhani's place in the upper echelons of the regime during Iran-tied terror plots around the world. He called the new president a "loyal servant of the regime."

"I wish I could believe Rouhani, but I don't -- because facts are stubborn things," he said, adding Iran's "savage record" contradicts Rouhani's "soothing rhetoric."

Netanyahu repeated the message he brought to the White House a day earlier, saying sanctions must remain in place -- as well as the credible threat of military action -- even as nuclear talks go forward. He said Israel would not allow Iran to produce a nuclear weapon, even if it stands alone in stopping the regime.

Netanyahu said the international community has Iran “on the ropes” and should strengthen its sanctions against the country.

“If you want to knock out Iran’s nuclear weapons program peacefully, don’t let up the pressure,” he said.

Netanyahu said to cease Iran’s nuclear program, its uranium enrichment capabilities must be stopped, its stockpiles of enriched uranium must be removed, its infrastructure for nuclear development must be dismantled, and all work at a reactor in Iraq – which is aimed at producing plutonium – must end.

Obama, sitting beside Netanyahu on Monday, agreed that "words are not sufficient" and western leaders need to see "actions."

He said it is "imperative" that Iran not possess a nuclear weapon, and added: "We have to test diplomacy."

He pledged to stay in "close consultation" with Israel.

Israeli leaders watched with dismay what they derisively call the "smiley campaign" by Iran's new president last week. Netanyahu, who contends Iran is using the gestures as a smoke screen to conceal an unabated march toward a nuclear bomb, said before boarding his flight to the U.S. that: "I will tell the truth in the face of the sweet talk and the onslaught of smiles."

An Iranian representative at the U.N. offered a rebuttal to Netanyahu's speech after he left the podium, saying that Iran is cooperating with the International Atomic Energy Agency, and repeated statements from Rouhani that the country's nuclear program is for peaceful purposes.

“We just heard an extremely inflammatory statement," the representative said. He said he didn't want to spend any time answering to Netanyahu's allegations, other than to "categorically reject" them.

The Associated Press contributed to this report.