Envoys from the P5Ư group of nations -- the US, UK, France, Russia and China - plus Germany -- will begin a new round of negotiations with Iran in Geneva later today.
Since 2006 the UN Security Council has imposed a series of sanctions on Iran over its controversial nuclear programme.
Obama said he didn't know if an agreement would come this week or next, but he said the bulk of the sanctions regime would remain.
He said the essence of the deal would be that they would halt advances on their nuclear programme.
