US Vice President Joe Biden and other top administration officials met with senior Democrats in a bid to persuade the Senate to hold off on new Iran sanctions, his office said Friday.

With Washington negotiating with Tehran's new leadership over the Islamic republic's nuclear drive, Biden sought to press pause -- at least for now -- on efforts by Congress to pass even tighter sanctions, to allow the talks to progress.

"No one is suggesting an open-ended delay for new sanctions, and there may come a point where additional sanctions are necessary," Biden's office said in a statement after he joined Secretary of State John Kerry and Treasury Secretary Jacob Lew in closed-door talks with Senate Majority Leader Harry Reid and other Democrats.

"At the same time, it is important for Congress to reserve its ability to legislate for the moment when it's most effective in order to give the current P5+1 negotiations the best chance to make real progress in achieving our shared goal of preventing Iran from obtaining a nuclear weapon."

The White House is keen to avoid a spat with Congress over the sensitive diplomatic issue, but many Republicans -- and some senior Democrats -- are skeptical of Obama's desire to put new sanctions on hold.

"We'll see what's the basis of that," Senator Robert Menendez told AFP before he and other members of the Banking Committee, which is considering legislation targeting Iran's oil industry, were briefed by Kerry and Lew.

Menendez afterward sounded unpersuaded, telling reporters "I'd have to hear something far more substantive from what I heard today to dissuade me" from moving on legislation.

Asked if he was worried Congress might pass new sanctions, Biden told Politico: "No I'm not concerned about it, the sanctions are tough."

Biden appeared to make inroads with some committee Republicans, including Senator Mike Johanns.

"I, like everyone, hope that whatever discussions will lead to a positive result," Johanns reportedly said after the briefing.

"So my attitude is, if there is some possibility of that occurring, I'd like to see that possibility go forward."

US officials meet with Iranian representatives November 7-8 as part of talks between Iran and six major powers -- Britain, China, France, Germany, Russia and the United States.

Number two Senate Democrat Dick Durbin sounded open to putting a hold on new sanctions.

"I think after 10 years of bitter confrontation, sanctions and all of the inflamed rhetoric, that it makes sense for us to be thoughtful on how and when we respond to the Iranians," Durbin said.

Since US and European Union sanctions went into effect in mid-2012, Iran's oil exports, which fund much of the government's expenditures, have plunged by half and inflation has surged, experts say.

Durbin said members of Congress will want to see how the administration "will measure good faith on the part of the Iranians," but that lawmakers would not hold off indefinitely.

"There has to be an indication about how long they are asking Congress to pause before initiating new sanctions," he said.