"The American people do not want a march to war," White House spokesman Jay Carney said on Tuesday. (Agencies)
The US, Britain, China, France, Germany, Iran and Russia will send top nuclear negotiators to Geneva next week to see whether they can push for a transparent nuclear programme in Iran.
"This is a decision to support diplomacy and a possible peaceful resolution to this issue," Carney said.
Iran maintains that its uranium enrichment is for energy production and medical research, not for any covert military objective. But until the recent election of President Hassan Rouhani, it refused to compromise in talks with world powers.
Carney said Americans "justifiably and understandably prefer a peaceful solution that prevents Iran from obtaining a nuclear weapon, and this agreement, if it's achieved, has the potential to do that".
Responding to Rouhani's promise of flexibility, President Barack Obama is keen on securing a diplomatic agreement. His telephone chat with Rouhani in September was the first direct conversation between US and Iranian leaders in more than three decades. The unprecedented outreach has angered US allies like Israel.
"The alternative is military action," Carney said.
"It is important to understand that if pursuing a resolution diplomatically is disallowed or ruled out, what options then do we and our allies have to prevent Iran from acquiring a nuclear weapon?" Carney said.
"The American people should not be forced to choose between military action and a bad deal that accepts a nuclear Iran," he said.
US Secretary of State John Kerry will take the administration's position directly to the Senate Banking Committee, which is mulling a new sanctions package against Iran.
"The secretary will be clear that putting new sanctions in place would be a mistake," State Department spokeswoman Jen Psaki said.
"What we are asking for right now is a pause, a temporary pause in sanctions," she told reporters. "We are not rolling them back."
A House committee, meanwhile, held a hearing to vent its frustration with Kerry and an Obama administration, who they believe should adopt a far tougher line with Tehran.
The Republican-led House of Representatives has already passed a bill to harden up the sanctions, but the Senate agreed to delay further action to allow diplomacy a chance to succeed.
The House of Representatives overwhelmingly approved new sanctions against Iran in July. The legislation blacklisted Iran's mining and construction sectors and committed to eliminate all Iranian oil exports worldwide by 2015.
"The American people do not want a march to war," White House spokesman Jay Carney said on Tuesday.