President Barack Obama today invoked the words of Mahatma Gandhi in his address to the UN General Assembly here as he remembered US envoy to Libya who was killed in violent protests that erupted in the aftermath of an anti-Islam film, saying the "crude and disgusting" video was no excuse for an "attack on America".

Obama took the stage at the UN General Assembly hall to address world leaders in what is his last international speech before the November 6 presidential elections.

"The attacks on our civilians in Benghazi were attacks on America. There should be no doubt that we will be relentless in tracking down the killers and bringing them to justice," said Obama, the second speaker of the general debate.

He began his address by remembering the memory of Christopher Stevens, the American ambassador who "helped the Libyan people as they coped with violent conflict, cared for the wounded, and crafted a vision for a future in which the rights of all Libyans would be who respected."

He said over the last two weeks, "a crude and disgusting video" has sparked outrage throughout the Muslim world.

"I have made it clear that the United States government had nothing to do with this video, and I believe its message must be rejected by all who respect our common humanity," the president said.

"The future must not belong to those who slander the prophet of Islam. Yet 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. Let us condemn incitement against Sufi Muslims and Shiite pilgrims. It is time to heed the words of Gandhi: 'Intolerance is itself a form of violence and an obstacle to the growth of a true democratic spirit'."

"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," Obama said.