UNITED NATIONS — In a U.N. role reversal yesterday, President Sarkozy of France adopted a harsh tone toward Iran, while President Bush focused his address to the U. N. General Assembly on the so-called soft issue of human rights, criticizing world tyrants. He ignored geopolitical battles in hot spots like Iraq, Iran, and North Korea, instead announcing a new set of sanctions against the military leaders of Burma.

Also at the United Nations yesterday, President Ahmadinejad of Iran, who just a day earlier cited freedom of speech as his reason for appearing at Columbia University and for backing the right of Holocaust deniers to continue their “research,” conducted a chaotic press conference. He refused to answer questions from Israeli reporters.

Mr. Ahmadinejad also ignored a question from an Israeli woman, Karnit Goldwasser, who asked for help in finding her husband, Ehud, a soldier who was kidnapped last summer in Lebanon. Mr. Ahmadinejad said God would protect his country from its Zionist enemies, and after speaking about his love of all religions, he appeared to mock members of the Bahai faith, asking, “Who is the divine prophet of the religion you are talking about?”

Greeting reporters on his way out of the press conference with handshakes, a beaming Mr. Ahmadinejad withdrew his hand quickly when a reporter told him he was a Zionist and proud of it. The Iranian president also skipped a traditional meal for those participating in the opening of the General Assembly, though the annual event was changed to dinner from lunch to allow Muslims observing Ramadan to participate. Last year, Mr. Ahmadinejad explained a similar absence by saying wine was served with the meal.

Mr. Bush highlighted human rights violations by the regimes in Cuba, Zimbabwe, Sudan, Belarus, Iran, and Syria, visibly irritating their leaders. The Cuban delegation to the assembly debate walked out in protest. “Bush is responsible for the murder of over 600,000 civilians in Iraq,” the Cubans said in statement. “He is a war criminal and has no moral authority or credibility to judge any other country.”

President Ortega of Nicaragua dedicated a large chunk of his assembly speech to defending his old comrade, Fidel Castro. President Chavez of Venezuela, who grabbed headlines in last year’s assembly by calling Mr. Bush “El Diablo,” announced at the last minute that he would skip this year’s event. He plans to host Mr. Ahmadinejad later this week.

It fell to Mr. Sarkozy to make the most striking reference to Iran in his speech. “There will be no peace in the world if the international community falters in the face of nuclear arms proliferation,” he said. “If we allow Iran to acquire nuclear weapons, we should incur an unacceptable risk to stability in the region and in the world.”

“I want to say here, in the name of France, that we can only resolve this crisis by combining firmness and dialogue,” the French president added.

French reporters asked Mr. Sarkozy, whose speech was hardest-hitting at the assembly yesterday and called for a “planetary new deal,” why he failed to mention Burma, as Mr. Bush had done. “If the president of the United States says something right, I don’t have to follow in his footsteps,” he said. In his address, Mr. Bush used much softer language than he had in past U.N. speeches. Rather than highlighting the military threat from countries he once dubbed the “axis of evil,” he said, “In Belarus, North Korea, Syria, and Iran, brutal regimes deny their people the fundamental rights enshrined in the Universal Declaration” of human rights.

By contrast, he said, “Brave citizens in Lebanon and Afghanistan and Iraq have made the choice for democracy, yet the extremists have responded by targeting them for murder.”

Mr. Bush, who in the past has challenged the United Nations’ “relevance,” made only one criticism of the world body in yesterday. It was aimed at the U.N. Human Rights Council, which was founded last year in an attempt to reform the much-criticized Human Rights Commission. The new council, he said, “has been silent on repression by regimes from Havana to Caracas to Pyongyang and Tehran — while focusing its criticism excessively on Israel. To be credible on human rights in the world, the United Nations must reform its own Human Rights Council.”

Mr. Ahmadinejad’s speech to the assembly touched on the same issues he has tried to advance since his arrival in New York, including his insistence that the “nuclear issue of Iran is now closed.” He highlighted the purported atrocities of the “Zionist regime,” saying the Palestinian Arabs are deprived of bare necessities “merely for the sin of seeking freedom.”

But it was after the speech, during a press conference that quickly got out of hand as frustrated reporters shouted questions and received circular non-answers, that Mr. Ahmadinejad made his mark. After noting that he tried to ask the same question last year at a press conference, a reporter for Israel’s Channel 10 television, Gil Tamary, asked if Iran intends to wipe Israel off the map. “Next question,” Mr. Ahmadinejad said. A reporter for Fox News, Jonathan Wachtel, asked a similar question, and Mr. Ahmadinejad responded by making a disparaging reference to the news organization. Finally, he answered a question about a purported threat to his country from Israel. “We turn a blind eye to their threats,” he said. “They will not be able to hurt us, with the help of God.”

A spokesman for the Israeli foreign minister, Tzipi Livni, said Israeli officials declined to attend Mr. Ahmadinejad’s U.N. speech because “there is no need to become an audience in this show.”