Obama says any agreement must allow Western powers to verify that Tehran isn't going to obtain an atomic weapon, and that even if Iran "cheated," the U.S. and others would have "enough time to take action."
The president tells CBS' "Sunday Morning" that "if we don't have that kind of deal, then we're not going to take it."
Big gaps remain to bridge if the sides are to reach a deal by the end of March deadline set by negotiators. The next round of talks is set to begin March 15.
Iran says the program is peaceful and exists only to produce energy for civilian use.
Senate Majority Leader Mitch McConnell, R-Ky., is insisting that Congress have a chance to review and vote on any deal, but acknowledges that he doesn't have the support yet to override a threatened veto by Obama.
"I'm hoping we can get 67 senators to assert the historic role of the Senate and the Congress in looking at matters of this magnitude. Obviously, the president doesn't want us involved in this. But he's going to need us if he's going to lift any of the existing sanctions. And so I think he cannot work around Congress forever," McConnell told CBS' "Face the Nation."