President Barack Obama told world leaders Tuesday that attacks on U.S. citizens in Libya "were attacks on America," and he called on them to join in confronting the root causes of the rage across the Muslim world.

"I do believe that it is the obligation of all leaders, in all countries, to speak out forcefully against violence and extremism," Obama said in a speech to the annual gathering of the United Nations General Assembly.

Obama also condemned the anti-Muslim video that helped spark the recent attacks, calling it "cruel and disgusting." But he strongly defended the U.S. Constitution's protection of the freedom of expression, "even views that we profoundly disagree with."

With U.S. campaign politics shadowing every word, Obama also warned that time to peacefully curb the Iranian nuclear crisis is running out.

Read more at NBC Los Angeles