Obama opened and closed his adress to the U.N. General Assembly with comments about Stevens, the U.S. ambassador to Libya who, along with three other American staffers, was killed two weeks ago at the U.S. Consulate in Benghazi.
Stevens, Obama said, "embodied the best of America."
In between, Obama said a nuclear-armed Iran won't be tolerated, called for a solution to the Israeli-Palestinian situation and condemned a U.S.-made video debasing the Prophet Muhammad while explaining the video, no matter how offensive it is, is protected speech.
"Make no mistake: a nuclear-armed Iran is not a challenge that can be contained," Obama said. "That is why a coalition of countries is holding the Iranian government accountable. And that is why the United States will do what we must to prevent Iran from obtaining a nuclear weapon."
He said leaders believe there is a window of opportunity for diplomacy and sanctions to work.
"But that time is not unlimited," he warned.
He also touched on the situation in Syria saying, "[We] again declare that the regime of [Syrian President] Bashar Assad must come to an end so that the suffering of the Syrian people can stop, and a new dawn can begin."
Obama said countries must "stand with those Syrians who believe in ... a Syria that is united and inclusive ... . Because we believe that the Syrians who embrace this vision will have the strength and legitimacy to lead."
Concerning the Israeli-Palestinian situation, Obama said the future "must not belong to those who turn their backs on the prospect of peace."
"Let us leave behind those who thrive on conflict, and those who reject the right of Israel to exist. The road is hard but the destination is clear -- a secure, Jewish state of Israel; and an independent, prosperous Palestine," he said. "Understanding that such a peace must come through a just agreement between the parties, America will walk alongside all who are prepared to make that journey."
Speaking specifically of the U.S.-made anti-Islam video that sparked deadly violence across the Middle East and Northern Africa, Obama reiterated that the U.S. government had nothing to do with the video "and I believe its message must be rejected by all who respect our common humanity. It is an insult not only to Muslims, but to America as well -- for as the city outside these walls makes clear, we are a country that has welcomed people of every race and religion."
But, he said, videos such as "Innocence of Muslims" that denigrate the Prophet Muhammad simply can't be banned in the United States.
"[Our] Constitution protects the right to practice free speech. Here in the United States, countless publications provoke offense," Obama said. "Like me, the majority of Americans are Christian, and yet we do not ban blasphemy against our most sacred beliefs. Moreover, as President of our country, and commander in chief of our military, I accept that people are going to call me awful things every day, and I will always defend their right to do so."
The United States protects speech because "in a diverse society, efforts to restrict speech can become a tool to silence critics and oppress minorities."
In this day and age of near-instant spread of pictures and comments, the question is how do people respond, Obama said.
"And on this we must agree: there is no speech that justifies mindless violence," he said to applause. "There are no words that excuse the killing of innocents."
He challenged those who condemn slandering the prophet of Islam.
"[To] be credible, those who condemn that slander must also condemn the hate we see when the image of Jesus Christ is desecrated, churches are destroyed, or the Holocaust is denied," Obama said to applause. "Together, we must work towards a world where we are strengthened by our differences, and not defined by them. That is what America embodies, and that is the vision we will support."
He repeated his administration's support for the Arab Spring, calling it a "season of progress."
But the recent violence and unrest demonstrate that "[true] democracy -- real freedom -- is hard work," he said.
The United States "will never retreat from the world," the president said.
"We will bring justice to those who harm our citizens and our friends," he said. "We will stand with our allies and are willing to partner with countries to deepen ties of trade and investment; science and technology; energy and development – efforts that can spark economic growth for all of our people, and stabilize democratic change."
What gives him hope, Obama said, "is not the actions of leaders; it is the people I've seen. ... These men, women and children of every race and every faith remind me that for every angry mob that gets shown on television, there are billions around the globe who share similar hopes and dreams. They tell us that there is a common heartbeat to humanity."
And after the killers are brought to justice for Stevens' death, the ambassador's "legacy will live on in the lives he touched," Obama said.
Those people "should give us hope," Obama said in conclusion. "They should remind us that so long as we work for it justice will be done; that history is on our side; and that a rising tide of liberty will never be reversed."
Charlize Theron not engaged to Sean Penn 'yet'
Pregnant Mila Kunis wins 'Best Villain' at MTV Movie Awards