US President Barack Obama says a "new chapter in American diplomacy" has been turned after the Arab Spring uprisings.
In a speech at the State Department, Mr Obama said the future of the US was bound to the Middle East by forces of economics, security, history and fate.
"It will be the policy of the US to promote reform, and to support transitions to democracy," he said.
Analysts say the speech is Mr Obama's first comprehensive response to revolts sweeping the Arab world.
Mr Obama said the top US priority across North Africa and the Middle East was to promote reform, and oppose the use of violence and oppression.
"We face a historic opportunity. We have a chance to show that America values the dignity of a street vendor in Tunisia more than the raw power of the dictator," he said.
"As Americans have been seared by hostage taking, violent rhetoric, and terrorist attacks that have killed thousands of our citizens - a failure to change our approach [in the Middle East] threatens a deepening spiral of division between the United States and Muslim communities," Mr Obama added.