Iran and a group of six world powers have exchanged detailed proposals during talks in Baghdad over Tehran's disputed nuclear activities.
U.S. State Department spokeswoman Victoria Nuland said the major powers put forward a proposal that includes reciprocal, step-by-step confidence-building measures at the talks.
"This is a proposal that reflects some initial confidence-building steps that we think match where we are now," she said.
Nuland added that the that the proposal "can pave the way for Iran to demonstrate that its nuclear program is for peaceful purposes."
She would not go into details of the plan.
Media reports say the proposal reportedly focuses on Western concerns about Iran's high-grade uranium-enrichment activities that would bring Tehran closer to being able to make a nuclear weapon.
Nuland said Iran had to comply with its international obligations if it wanted to build trust with its international partners.
"What we're looking for at the end of this road is full compliance by Iran with its international obligations, and full ability of the IAEA to inspect and verify any obligations that [Iran] has undertaken," she said.
"What we're talking about in terms of this Baghdad round is a first set of confidence-building steps."
Iranian media, however, slammed the world powers' proposal, calling it "unbalanced" and said it failed to address other outstanding issues.
State media also said Tehran had presented its own new, five-point, "comprehensive" package of proposals to the world powers at the Baghdad meeting.
It said the package included "nuclear and nonnuclear" issues and "concrete steps."
Iran says all its nuclear activities are peaceful, but Western countries accuse Iran of secretly trying to develop nuclear weapons.
Iran has previously declined to halt work on 20 percent enrichment -- a level that would bring the Islamic republic closer to being able to make a nuclear weapon.
The Baghdad talks are the first between Iran and the six powers -- Britain, China, France, Germany, Russia, and the United States -- since April.
'No Instant Solution"
Speaking earlier in Moscow, Russian Foreign Minister Sergei Lavrov told reporters that Iran appeared ready to agree to specific steps to end the standoff. "We have to understand that there will be no instant solution, it will be a process," he said.
"But at every stage of this process, conducted in accordance with the principles of gradual, reciprocal steps, we want to see concrete results: Iran takes a step to meet the demands of the international community; the international community takes steps that weaken sanctions pressure on Iran and so forth until we reach the point when it is clear to all that Iran's nuclear program has no military aspect."
Israeli Defense Minister Ehud Barak urged the world powers on May 23 not to make concessions in the talks. He told Israeli public radio that "without strengthening the current painful sanctions, Iran will continue towards a nuclear capability."
Israel, which views a potential Iranian nuclear bomb as a threat to the Jewish-led state's existence, says military strikes on Iran remain an option.
Ahead of the talks, Iran agreed in principle to give the International Atomic Energy Agency (IAEA) access to sites, documents and experts that inspectors suspect may be connected to weapons projects.
Banking, Oil Sanctions
IAEA chief Yukiya Amano said he expected that the agreement, not yet signed, would include access to the Parchin military site near Tehran.
Inspectors believe Iran built a containment building at Parchin in 2000 for testing explosions related to nuclear weapons development. IAEA inspectors last visited Parchin in 2005, but were not granted access to the containment facility.
After the announcement of the agreement in principle on May 22, Tehran said it would be seeking concessions from the powers at the Baghdad talks.
Tehran wants Western powers to lift sanctions on its banking and oil sectors -- measures that target the government's main sources of foreign revenue.
The West says the sanctions are necessary to force Iran to prove its nuclear program is not aimed at developing atomic weapons. Iran says it has never sought to develop a nuclear bomb.
Iran is already under four rounds of UN Security Council sanctions aimed at forcing it to suspend uranium enrichment and other aspects of its nuclear and missile programs until all outstanding questions about its intentions are answered.
With reporting by Reuters, AP, and AFP