NEW YORK (CNN) -- Iranian President Mahmoud Ahmadinejad on Monday challenged a university audience to look into "who was truly involved" in the September 11, 2001, terrorist attacks, defended his right to question established Holocaust history and denied there were gay Iranians.

When pressed about the harsh treatment of women, homosexuals and academics who challenge Iran's government, Ahmadinejad painted a rosy picture, saying, "Women in Iran enjoy the highest levels of freedom," he said.

He elicited laughter and boos from the audience at Columbia University when he said, "In Iran, we don't have homosexuals, like in your country."

His remarks, which lasted about an hour, made several general references to God, religion and science. He portrayed himself as an academic, misunderstood and unfairly criticized in the United States.

Ahmadinejad is in New York to address the United Nations General Assembly on Tuesday. He spoke at the invitation of Columbia's president, Lee Bollinger, who in his introduction excoriated the leader by saying he "exhibit[s] all the signs of a petty and cruel dictator."

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Blaming his schedule, Ahmadinejad left Columbia after his speech before answering many questions posed to him, Bollinger said.

Hundreds gathered to protest Ahmadinejad's appearance, incensed that a leader who has publicly denied the Holocaust and called for the destruction of the state of Israel was given a prestigious forum to espouse his beliefs.

Christine C. Quinn, speaker of the New York City Council, said Columbia should not be giving Ahmadinejad a platform. "All he will do on that stage ... is spew more hatred and more venom out there to the world," she said.

Hamid Dabashi, a professor of Iranian studies at Columbia, called the whole forum "misguided."

Refusing to back off of his stance on Israel, Ahmadinejad again questioned whether the Holocaust happened.

"If the Holocaust is a reality of our time, a history that occurred, why is there not sufficient research that can approach the topic from different perspectives?" he asked.

The Iranian leader has made statements in the past suggesting Israel be politically "wiped off the map," though he insists that can be accomplished without violence. See some of Ahmadinejad's controversial remarks »

While he would not respond with a "yes" or "no" when asked Monday if he sought the destruction of Israel, he said the status of Israel should be determined by a free election.

"Let the people of Palestine freely choose what they want for their future," he said.

Ahmadinejad has drawn fire for defying international demands that Iran halt production of enriched uranium.

At Columbia, he said Iran is a member of the International Atomic Energy Agency, the world's central nuclear technology governing body, and has submitted many times to IAEA inspections. "Over and over again the agency's reports indicate that Iran's activities are peaceful, that they have not detected a deviation," he said.

Washington and other nations accuse Tehran of trying to create a nuclear weapons program. Watch reaction to Ahmadinejad speaking at Columbia University »

Ahmadinejad said Iran questions "the way the world is being run and managed today."

But he said Iran would hold talks with the U.S. government "under fair and just circumstances."

U.S. officials have said Iranian explosives and weapons are making their way to Shiite Muslim militias in Iraq's sectarian conflict and have been used against U.S. troops in the four-year-old war. U.S. commanders have said they have captured Iranian agents involved in supplying those weapons to the militias, some of which have longstanding ties to Iran.

On this point, Ahmadinejad employed a tactic he used often Monday -- answering questions with more questions.

Bollinger asked, "Why is your government providing aid to terrorists? Will you stop doing so and permit international monitoring to certify that you have stopped?"

Through a translator, Ahmadinejad replied, "Well, I want to pose a question here to you. If someone comes and explodes bombs around you, threatens your president, members of the administration, kills the members of the Senate or Congress, how would you treat them? Would you reward them or would you name them a terrorist group? Well, it's clear. You would call them a terrorist."

Earlier Ahmadinejad had said he wanted to visit ground zero in New York to "pay his respects" to those who died in the attack on the twin towers at the World Trade Center. Several groups were outraged. Security became an issue and the visit was canceled. Asked what he hoped to accomplish there, the Iranian president said it was unfair he could not extend his sympathies to victims of the September 11, 2001 terrorist attacks.

Addressing the press directly, he seemed to make a connection between the "root causes" of the September 11, 2001 attacks and a solution in Iraq and Afghanistan.

"If the root causes of 9/11 are examined properly -- why it happened, what caused it, what were the conditions that led to it, who truly was involved, who was really involved -- and put it all together to understand how to prevent the crisis in Iraq, fix the problem in Afghanistan and Iraq combined."

He stressed repeatedly that Iran wants to negotiate with the United States and other nations, several times describing Iran as a "cultured" and "civilized" nation.

"I think that if the U.S. administration, if the U.S. government puts aside some of its old behaviors, it can actually be a good friend for the Iranian people, for the Iranian nation," he said. "For 28 years, they've consistently threatened us, insulted us, prevented our scientific development, every day, under one pretext or another."

As he ended his talk at Columbia, he invited faculty and students to visit any university in Iran they choose.

"We'll give you the platform. We'll respect you 100 percent. We will have our students sit there and listen to you, speak with you, hear what you have to say," he assured.

Earlier Monday, in a question-and-answer videoconference with the National Press Club, Ahmadinejad said the Middle East can govern itself without interference from the United States and other Western nations.

Speaking from New York to the luncheon in Washington, Ahmadinejad said Iran wanted to see "an independent powerful Iraq ... which will benefit the entire region."

"We are two nations interconnected," he said of Iran and Iraq. "We are brothers and friends."

But he said the region didn't need U.S. help.

"We oppose the way the U.S. government tries to manage the world. ... We propose more humane methods of establishing peace," he said. E-mail to a friend

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