The US administration stepped up its battle Tuesday to thwart moves by lawmakers to tighten sanctions on Iran, warning that would jeopardize tough negotiations on Tehran's nuclear program.

Secretary of State John Kerry videotaped a message to members of Congress warning against any new sanctions during the six-month period of talks laid down in a deal struck at the weekend in Geneva.

Seeking to tell lawmakers what the deal "does and does not do," the top US diplomat tried to dispel what he called the "misinformation" surrounding the agreement.

"It does not lift the current architecture of our sanctions. Our sanctions are basically banking and oil sanctions and those sanctions will stay in place," Kerry says in the video.

And he stresses: "We all know that if the agreement falls apart Iran is going to quickly face even tougher sanctions."

Work will begin immediately on hammering out the final agreement which will have to satisfy the concerns of several powers including Israel, and Gulf allies like Saudi Arabia and the United Arab Emirates, which are wary about the US rapprochement with Iran.

"The whole world has an interest in making sure that this is a peaceful program," Kerry says in the video.

Kerry, and the US administration of President Barack Obama, are seeking to head off moves in Congress to draw up new sanctions against Iran.

In a round of phone calls to lawmakers, Kerry would urge that "passing any new sanctions legislation during the course of the negotiations, in our view, would be unhelpful and could put the success of the outcome at risk," State Department spokeswoman Jen Psaki said.

The White House echoed the message, warning any "additional sanctions before this diplomatic window could be pursued would undermine our credibility about the goal of these sanctions."

Deputy White House spokesman Josh Earnest added: "We're not sanctioning just for the sake of sanctions and we're not sanctioning the Iranians specifically to punish them.

"We have these sanctions in place to pressure Iran to consider and pursue a diplomatic option."

Iran and major powers reached an accord in Geneva on Sunday, under which the Islamic state has agreed to freeze parts of its nuclear program in exchange for an estimated $7 billion of relief from crippling sanctions.

Kerry has already led a blitz on Congress, where lawmakers have threatened to take up new legislation against Iran when they return in early December from their recess for the Thanksgiving holidays.

On Tuesday, he spoke with Senator Bob Menendez, who took over from Kerry earlier this year as chairman of the powerful Senate Foreign Relations committee.

Menendez warned in a statement last week that he would "work together to reconcile Democratic and Republican proposals over the coming weels and to pass bipartisan Iran sanctions as soon as possible."

But under the Geneva deal Washington committed to "refrain from imposing new nuclear-related sanctions" for the six months during which world powers will seek to hammer out a comprehensive settlement.

New sanctions would "violate the spirit" of the interim accord, Psaki warned, and could divide the group known as the P5+1 -- Britain, France, Germany, China, Russia and the United States.

"Other countries would think that the United States is not living up to our end of the bargain in terms of giving the negotiations a chance," she warned.

The next step is that technical teams from both Iran and the P5+1 will meet to "tee up the implementation" of the deal, she added.

The promised sanctions relief would be metered out in installments.

It's not "an all-at-one-time or .. a spigot that's turned all the way on. It would be a slow process that obviously we control, and some of those details are still being worked out," she said.

Under the deal, Iran will allow daily inspections of its nuclear facilities; halt any uranium enrichment above 5 percent purity as well as neutralize its stocks of 20 percent enriched weapons-grade uranium; halt construction on its heavy water reactor at Arak and not install new centrifuges at its Natanz enrichment plant.

In return, the European Union and United States will suspend sanctions on Iran's petrochemical exports, as well as its gold and precious metals, and ease US sanctions on its auto industry.