"But what I've also said to him directly is that we both have an interest in preventing chaos, we both have an interest in preventing terrorism. The situation in Syria right now is untenable. As long as Mr. Assad's in power, there is going be some sort of conflict there."
Obama's interview was taped Friday and aired Sunday.
Despite Obama's calls for Assad to leave power, Obama reiterated that he would not use military force to achieve that objective. He said securing Syria's chemical weapons is his "primary concern."
In setting out one of the most ambitious arms-control efforts in history, the U.S. and Russia reached an agreement to inventory Syria's chemical weapons program and seize all its components. The agreement includes imposing penalties if the Assad government fails to comply.
In a written statement following the agreement, Obama said the world expects Syria to live up to its public commitments to hand over its chemical weapons stockpile. He also warned that the U.S. was prepared to act if Syria falls short.
The U.S. and others blame Assad's government for an Aug. 21 gas attack in the suburbs of Damascus, the Syrian capital. Assad denies the charge, blaming Syrian rebels. More than 1,400 people died, according to U.S. estimates, the latest victims of Syria's 2½-year-old civil war.
Polls showed relatively little support among Americans for a military strike against Syria, even after the Obama administration's efforts to argue that punishing the Assad government for violating international norms of warfare was in the security interests of the U.S.
Obama ordered preparations for American airstrikes, but he decided instead to ask for authorization from Congress for military action. Then came the Russian proposal for international control of Syria's chemical weapons, and Obama asked Congress, already largely opposed to military intervention, to delay a vote.The deal to destroy Syria's chemical weapons also offers the potential for reviving international peace talks to end a civil war that has claimed more than 100,000 lives and sent 2 million refugees fleeing for safety and threatens the stability of the entire Mideast.
In Congress, Republican Sens. John McCain of Arizona and Lindsey Graham of South Carolina, who are among Obama's sharpest foreign-policy critics and support greater U.S. assistance for Syria's rebels, said the agreement will embolden enemies such as Iran.
House Democratic leader Nancy Pelosi of California credited the president's "steadfast leadership" for "making significant progress in our efforts to prevent the use of weapons of mass destruction."