Claims by top Iranian leaders that Washington is misrepresenting terms of an interim nuclear deal left the White House with a new political headache Thursday as it battles to build support for the pact.

Comments by President Hassan Rouhani and Foreign Minister Javad Zarif left the White House parrying accusations that it had underplayed concessions it made in the interim deal, which went into force this week, and overplayed Iran's commitments.

"The White House tries to portray it as basically a dismantling of Iran's nuclear program," Zarif said in an interview with CNN, denying that Tehran had many any such promise.

"If you find a single, a single word that even closely resembles dismantling or could be defined as dismantling in the entire text, then I would take back my comment," Zarif said in the interview broadcast on Wednesday.

In another CNN interview, President Hassan Rouhani suggested that Iran has a different vision of the terms of a final nuclear deal from Washington -- which expects Tehran to dismantle important parts of its nuclear program.

Asked whether Iran would destroy centrifuges used to enrich uranium at its plants, Rouhani said: "Not under any circumstances. Not under any circumstances."

White House spokesman Jay Carney argued in response that Washington had known all along that Iran would try to "spin" the deal, which went into force this week, to its own advantage and for domestic political reasons.

"This is all about what they do, not what they say," Carney said, and also said that the question of "dismantling" aspects of Iran's nuclear program was more relevant to discussion about the comprehensive final agreement the United States and western powers hope to make with Iran rather than the interim deal.

The comments by Zarif and Rouhani forced the administration into a new attempt to defend the nuclear deal as it fights an effort by a bipartisan group of lawmakers to impose new sanctions on Iran which President Barack Obama fears could scupper the diplomatic process.

Republican Senator Mark Kirk, one of the top backers of new sanctions, seized on Zarif's remarks on Thursday.

"15k centrifuges must be removed to thwart Iranian bomb," Kirk wrote on Twitter.

"Bipartisan Nuclear Weapon Free Iran Act requires #Iran 2 dismantle illicit nuke infrastructure 2 prevent Iranian bomb; time 4 Senate 2 vote," he said in another tweet.

The Obama administration has conceded that it will not be possible to conclude the perfect deal with Iran to end its nuclear program that Israel and hawkish lawmakers would like, but is pushing for verifiable concessions from Tehran that would put it much further away from producing a nuclear weapon.

Chances of concluding a deal, in delicate political environments in Washington and Tehran, might in fact hinge on both sides being able to emerge from talks claiming victory, and able to represent the agreement in a different light to respective domestic audiences.

Under the nuclear deal, Iran has halted production of enriched uranium above five percent purity and begun converting medium enriched uranium while halting work on reactors at the Natanz, Fordo and Arak plants.

In return, Western powers are loosening sanctions in a package worth $6 to $7 billion, including $4.2 billion in frozen overseas foreign exchange assets.