The US negotiator on Iran's nuclear program appealed Friday to Congress to put on hold a bid for even tighter sanctions after hopeful signs in talks with Tehran's new leadership.

"We are beginning to understand each other, to see each other's needs and the aspirations of the people of each of our countries," Undersecretary of State Wendy Sherman told the Voice of America's Persian service.

On a congressional proposal for tougher sanctions, Sherman said: "We think that this is a time for a pause, to see if these negotiations can gain traction."

Sherman represented the United States at October 15-16 talks between Iran and six major powers aimed at easing concerns over the clerical regime's contested nuclear work.

Sherman at the time expressed guarded optimism at striking a deal with Iran's new moderate leadership and called on Congress to tread cautiously on new sanctions ahead of the next round of talks on November 7 and 8.

State Department spokeswoman Jen Psaki, echoing Sherman, said that President Barack Obama's administration wanted congressional action to be "aligned with our negotiating strategy."

"While we understand that Congress may consider new sanctions, we think this is a time for a pause, as we asked for in the past, to see if negotiations can gain traction," she said.

President Hassan Rouhani, elected on a platform of repairing Iran's troubled economy, last month spoke by telephone to Obama in the first contact between the nations' leaders since the 1979 Islamic revolution overthrew the pro-Western shah.

The US Congress has championed punishing sanctions on Iran. Days ahead of Rouhani's inauguration, the House of Representatives easily approved a bill to toughen already sweeping sanctions on Iran's oil exports.

Many House members voiced concerned about the security of Israel, whose Prime Minister Benjamin Netanyahu has branded Rouhani a "wolf in sheep's clothing."

But the proposal has not come up to a vote in the Senate. Leading senators from both parties, including Senate Foreign Relations Committee chairman Robert Menendez, have said they will suspend implementation of new sanctions if Iran takes verifiable steps such as halting uranium enrichment.