In his first major address on the subject since the Arab Spring of democracy movements swept the Mideast, he said: "We have embraced the chance to show that America values the dignity of the street vendor in Tunisia more than the raw power of the dictator."
"There must be no doubt that the United States of America welcomes change that advances self-determination and opportunity," he said.
"Yes, there will be perils that accompany this moment of promise. But after decades of accepting the world as it is in the region, we have a chance to pursue the world as it should be."
Referring to the killing of Osama bin Laden in a US commando raid in Pakistan, Obama said: "We have dealt Al Qaeda a huge blow by killing its leader Osama bin Laden. Bin Laden was no martyr. He was a mass murder who offered a message of hate."
Obama portrayed Osama as hostile to the democracy movements sweeping the region and increasingly irrelevant in the days leading up to his death.
Osama "rejected democracy and individual rights for Muslims in favor of violent extremism," Obama said. "His agenda focused on what he could destroy, not what he could build."
"Through the moral force of non-violence, people of the region have achieved more change in six months than terrorists have accomplished in decades," Obama said.
He added: "It will be years before this story reaches its end."
