U.S. State Department spokeswoman Victoria Nuland said that the Obama administration is working to solve the Iranian nuclear crisis through "tough diplomacy".

“The U.S. is looking forward to the IAEA report on Iran's nuclear progress and hope that it will lead to a hardening of the international position towards the Islamic Republic,” Nuland said.

She added that the U.S. has said time after time that it isn't seeking a military confrontation with Iran and that it remains the US position.

A report in The Guardian, without citing a source, said earlier this week that Britain's Defense Ministry believed the United States may accelerate plans for missile strikes at some key Iranian facilities and cited British officials as saying it would seek and receive military help from Britain for any mission.

UN diplomats in New York and government officials elsewhere called the Guardian report exaggerated. They said Israel would be more likely to use military force against Iranian nuclear facilities than the United States, which is bogged down in conflicts in Iraq and Afghanistan.