UNITED NATIONS (AP) — Confronting global tumult and Muslim anger, President Barack Obama exhorted world leaders Tuesday to stand fast against violence and extremism, arguing that protecting religious rights and free speech must be a universal responsibility and not just an American obligation.

“The impulse towards intolerance and violence may initially be focused on the West, but over time it cannot be contained,” Obama warned the U.N. General Assembly in an urgent call to action underscored by the high stakes for all nations.

The gloomy backdrop for Obama’s speech — a world riven by deadly protests against an anti-Islamic video, by war in Syria, by rising tension over a nuclear Iran and more — marked the dramatic shifts that have occurred in the year since the General Assembly’s last ministerial meeting, when democratic uprisings in the Arab world created a sense of excitement and optimism. Obama had tough words for Iran and condemned anew the violence in Syria as Bashar al-Assad tries to retain power.

Six weeks before the U.S. presidential election, an unmistakable campaign element framed Obama’s speech as well: The president’s Republican rival, Mitt Romney, has tried to cast him as a weak leader on the world stage, too quick to apologize for American values.

Romney, speaking at a Clinton Global Initiative forum just miles from the U.N., avoided direct criticism of Obama in deference to the apolitical settings of the day, but he said he hoped to return a year later “as president, having made substantial progress” on democratic reforms.

Obama, likewise, avoided direct politicking in his speech but offered a pointed contrast to his GOP opponent’s caught-on-tape comment that there is little hope for peace between Israelis and Palestinians.

“Among Israelis and Palestinians,” Obama said, “the future must not belong to those who turn their backs on a prospect of peace.”

Secretary-General Ban Ki-moon’s opening state-of-the-world speech to the General Assembly’s presidents, prime ministers and monarchs sketched the current time as one when “too often, divisions are exploited for short-term political gain” and “too many people are ready to take small flames of indifference and turn them into a bonfire.”

The leaders are assembled here as anger still churns over a made-in-America video that mocked the Prophet Muhammad. The video helped touch off protests throughout the Muslim world that have left at least 40 people dead, including the U.S. ambassador to Libya.

Obama, a onetime professor of constitutional law, delivered what amounted to a lecture on what he presented as the bedrock importance of free speech, even if it comes at a price.

He stressed that just as the “cruel and disgusting” video did not reflect U.S. values, the backlash against it did not represent the views of most Muslims. Still, he said, “the events of the last two weeks speak to the need for all of us to address honestly the tensions between the West and the Arab world that is moving towards democracy.”

Obama said the notion of controlling information is obsolete in the Internet age, “when anyone with a cellphone can spread offensive views around the world with the click of a button.” But he said leaders must be swift to respond to those who would answer hateful speech with violence and chaos.

In his last international address before the November elections, the president had strong words for the leaders in Iran and Syria but broke no new ground on any actions the U.S. might take.

He warned that while there is still hope of resolving the dispute over Iran’s nuclear program through diplomacy, “that time is not unlimited.” Without laying out specifics, he added: “The United States will do what we must to prevent Iran from obtaining a nuclear weapon.”

As for the rising violence in Syria, Obama told the U.N. delegates, “The future must not belong to a dictator who massacres his people. If there is a cause that cries out for protest in the world today, it is a regime that tortures children and shoots rockets at apartment buildings. We must remain engaged to assure that what began with citizens demanding their rights does not end in a cycle of sectarian violence.”

Obama’s defense of free speech was respectfully received by world leaders. Yet it was clear that different understandings abound on the proper exercise of free expression.

The foreign minister of Indonesia, home to the world’s largest Muslim population, said Obama’s speech was a “clarion call” for all nations to reject intolerance, calling it “an issue that galvanizes all of us.” But Foreign Minister Marty Natalegawa added that freedom of expression should be exercised with consideration to morality and public order.

Dina Zakaria, a spokesman for the Muslim Brotherhood’s political party Freedom and Justice, said cultural differences between the U.S. and the Muslim and Arab world over the limitations of freedom of expression will persist.

“No one can argue against freedom of expression, but the Western understanding of it is different from ours,” she said. “Will this freedom allow for contempt of religion? For us it is different. For us it is a red line as Muslims and Christians as well.”