A State Department spokesman on Friday signaled that the president's mandate that Iran has two weeks to permit inspections of its recently unveiled uranium refinement plant was not "written in stone."

"I don't think that there's a hard-and-fast deadline," State Department spokesman Ian Kelly said during Friday's press briefing, after a reporter asked what the consequences of Iran's inaction might be.

"I think that we've made it quite clear this was a matter of some urgency; that we expected [Iran] to take urgent and concrete steps to open up this facility, and not only just open it up but also make sure that we were able to — or that the IAEA would be able to — talk to some of the engineers there and see documents and plans," Kelly added. 

President Barack Obama first issued the tough two-week deadline in a speech following Thursday's meetings between Iran and the P5+1, a coalition of British, Chinese, French, German, Russian and U.S. officials. At the time, Obama reiterated the U.S. approach to Iran's nuclear program would be tough — especially so, he added, if Iranian President Mahmoud Ahmadinejad failed to provide nuclear inspectors "unfettered access" to its uranium facilities.

"In pursuit of that goal, today's meeting was a constructive beginning, but it must be followed with constructive action by the Iranian government," Obama said on Thursday.

"We're not interested in talking for the sake of talking," the president added.

But Kelly on Friday seemed to downplay any diplomatic expectations. He stressed during his briefing that the Obama administration would not commit to a response or punishment, much less a deadline, until it could coordinate with the International Atomic Energy Association (IAEA).

"I don't know that it's written in stone, necessarily," Kelly repeated about the deadline. "But I think we'll find out more details when — after [IAEA head Mohamed] ElBaradei's trip."