While condemning the violence sparked by a video made in California that depicts the Prophet Mohammad as a womanizer, fool and child abuser, several Muslim leaders called for international action to outlaw acts of blasphemy.
Obama - while repeating his condemnations of the video as "crude and disgusting" and stressing that the U.S. government had nothing to do with its production - staunchly defended free speech.
"The strongest weapon against hateful speech is not repression, it is more speech - the voices of tolerance that rally against bigotry and blasphemy," Obama said.
Saying it is necessary to "honestly address the tensions between the West and the Arab world" moving toward democracy, Obama said he did not expect everyone to agree with him.
"However, I do believe that it is the obligation of all leaders in all countries to speak out forcefully against violence and extremism," he said. "There is no speech that justifies mindless violence."
'Call me awful things'
"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," Obama said, drawing applause and some laughter.
The U.S. view, however, was not embraced by all sides at the General Assembly.