Ehud Olmert, the former prime minister of Israel, plunged on Sunday into the country’s growing debate over Iran policy with harsh criticism of his successor, Benjamin Netanyahu.

As several recently retired top security officials have done, Mr. Olmert urged Mr. Netanyahu’s government not to rush into unilateral military action against Iran’s suspected nuclear weapons program.

But Mr. Olmert went much further. Drawing boos from a largely American audience in New York, he fired off a wide-ranging broadside against Mr. Netanyahu’s foreign policy, saying that the prime minister was unprepared to offer meaningful compromise to Palestinians, disrespectful to the United States and dismissive of the international community at a time when Israel particularly needs foreign support to prevent Iran from obtaining nuclear weapons.

“A nation has the right to determine what it should do to defend itself,” Mr. Olmert said at a conference held in a Manhattan hotel by The Jerusalem Post. “But when at the same time we ask the United States and other countries to provide us with the means to do it, no one is entirely independent to act, irrespective of the positions and attitudes and policies of other countries.”

Since leaving office in 2008, Mr. Olmert has often urged caution concerning Iran. His remarks on Sunday were noteworthy for their place and time — before an audience of some of Mr. Netanyahu’s strongest American supporters, and only a few days after Israel’s top military officer suggested that the threat posed by Iran was less urgent than Mr. Netanyahu has said, and the former head of Israel’s internal security service said the prime minister had “messianic feelings.”

Illustrating how visceral the debate has become, and how entwined it is with politics in both Israel and the United States, some in the crowd peppered Mr. Olmert with shouts of “Naïve!” and “Neville Chamberlain!” and booed loudly when he called for a less confrontational stance toward President Obama, whose political opponents Mr. Netanyahu has openly courted.

“You have to respect him,” Mr. Olmert said of Mr. Obama. “He is the president of the most powerful nation on earth, and happens to be a friend of Israel.” When boos rang through the conference room in response, he joked, “I can see that this hall is full of Democrats.”

Mr. Olmert was booed again when he declared that while Israel should prepare the military ability to strike Iran’s nuclear program as a last resort, it should first push for American-led international action against Iran, including sanctions and possible joint military action.

This time, he responded caustically.

“As a concerned Israeli citizen who lives in the state of Israel with his family and all of his children and grandchildren,” he said, “I love very much the courage of those who live 10,000 miles away from the state of Israel and are ready that we will make every possible mistake that will cost lives of Israelis.”

Israeli politics suffused Sunday’s conference. Mr. Olmert noted that critics of Mr. Netanyahu have ascribed the prime minister’s urgent rhetoric on Iran to political considerations. His remarks on the Palestinian issue may add to recent pressure on Mr. Netanyahu to tack to the left before the next election, which is now expected as early as the fall.

Mr. Netanyahu plans to call this week for a renewal of talks with the Palestinians, proposing direct negotiations with no preconditions, according to The Israel Project, an advocacy group that promotes the positions of the Israeli government.

Although Mr. Olmert is embroiled in a corruption scandal at home and faces a possible prison term, Israel is a country where political comebacks are common, so his remarks in New York on Sunday may reflect domestic political calculations of his own.

His Kadima Party was formed to offer a center-right alternative to Mr. Netanyahu’s conservative Likud bloc.

Gilad Erdan, the Israeli environment minister, defended the government’s policy on Sunday, saying that Iranian nuclear weapons could provide an umbrella to militant groups like Hamas and Hezbollah or even “find their way into terrorist hands,” calling that scenario “too terrifying to even consider.”

In an interview after his appearance at the conference, Mr. Olmert said he was expressing legitimate concerns shared by most people in the Israeli security establishment, “present and past,” including many who have not spoken publicly.

Two such former officials, Gabi Ashkenazi, the former chief of staff of the Israeli Defense Forces, and Eliezer Shkedy, the former air force commander, told the conference on Sunday that an international approach to Iran was preferable.

In the past, Mr. Shkedy has, like Mr. Netanyahu, compared the threat of a nuclear-armed Iran to the Holocaust.

At the conference, The Jerusalem Post released results of a recent poll indicating that most Israelis would back a military strike on Iran by an American-led coalition but fewer than half by Israel alone.

Mr. Olmert said in the interview that Israel should quietly build American support behind the scenes, and not publicly declare that it will act with or without America, given its dependence on American military aid and hardware.

“America is not a client state of Israel — maybe the opposite is true,” he said. “Why should we want America to be put in a situation where whatever they do will be interpreted as if they obeyed orders from Jerusalem?”

Mr. Olmert warned that Mr. Netanyahu and his defense minister, Ehud Barak, having likened Iran to Nazi Germany, may find themselves unable to back down from military action.

“They talk too much, they talk too loud,” he said in the interview. “They are creating an atmosphere and a momentum that may go out of their control.” (Copyright 2012 The New York Times Company 04/30/12)