Washington, Dec 21 

US President Barack Obama said Friday that there is the possibility of a resolution to Iran's nuclear issue which has been a challenge to the US national security for over a decade.

With an interim deal reached between world powers and Iran in November, "we had the first halt and in some cases some rollback of Iran's nuclear capabilities. The first time that we've seen that in almost a decade," reported Xinhua citing Obama at a year-end press conference.

He urged lawmakers not to impose new sanctions on Iran now, but said he was "not surprised" over such talk in the Congress as "the politics of trying to look tough on Iran are often good when you're running for office or if you're in office".

Twenty-six senators introduced a bill Thursday that would impose further sanctions on Iran if Tehran fails to comply with the November interim deal. It is not clear if or when the bill could see a vote on the Senate floor.

The White House deemed the move "unnecessary" and threatened to veto the bill if it were enacted.

"We don't think it will be enacted. If it were enacted, the president would veto it," White House spokesman Jay Carney said at a press briefing Thursday.

Obama said it is very important for the US to test the possibility that Iran's nuclear program would not be weaponised, because the alternative is a potential conflict with "all kinds of unintended consequences."

He reiterated his intention of solving the Iran nuclear issue diplomatically, which he said is also the preference of the Congress and the American people.

Obama believed that Iran knows well the consequences if negotiations fail. "Congress would be more than happy to pass more sanctions legislation. We can do that in a day, on a dime."

"If we're serious about negotiations, we've got to create an atmosphere in which Iran is willing to move in ways that are uncomfortable for them," the US president added.