The Obama administration said Monday that its patience on Iran's nuclear program is limited, warning that Tehran must make a choice between further integration with the international community and further isolation.

"The President has said that our patience is not unlimited. He's indicated that we're willing to give a preponderance of attention to the engagement track until the end of the year, and if we don't get a positive response, we're going to start shifting our focus over to the other track, the track of pressure," said State Department spokesman Ian Kelly.

"We have offered a path of cooperation that could lead to further integration with the international community. That's the IAEA offer that's on the table. And it's unfortunate that they haven't been able to respond positively on that," said Kelly, adding "the other choice they have is further isolation."

According to a deal brokered by the International Atomic Energy Agency (IAEA), about 70 percent of Iran's enriched uranium would be shipped abroad in exchange for fuel robs for research use. But Iran has said that it would consider a Uranium-for-fuel swap inside the country.

President Mahmoud Ahmadinejad announced Sunday that Iran will build 10 new uranium enrichment facilities, with work starting on at least five sites within two months in order that 250 to 300 tons of nuclear fuel can be produced annually.

The United States, its European allies and Israel claim that Iran's nuclear program is aimed at developing nuclear weapons, while the UN Security Council also requires Iran to suspend its uranium enrichment activity.

However, Iran insists that its nuclear plan is only for peaceful purposes, and continues its uranium enrichment activity despite the pressure from the western countries and relevant resolutions and sanctions of the United Nations.