He calls the deal a "golden page" in the country's history.
Iranian officials have floated the idea of a prisoner exchange involving American citizens held in Iran.
The warning comes after the U.S. tightened visas for people for people who have visited Iran or hold dual Iranian nationality.
The new measure passed by Congress will prevent visa-free travel to the U.S. for people who have visited Iran or hold Iranian nationality.
The text would close the International Atomic Energy Agency's 12-year investigation of Tehran's past activities.
Iran is more willing to engage with the U.N. than in previous years, the report's author said.
Rouhani needs sanctions lifted quickly; Khamenei just ordered him to move slowly.
British officials and business leaders say the rise of China is impossible to ignore: China's economy is four times the size of Britain's.
Khamenei said Iran would stop implementing the deal if the six powers imposed any new sanctions.
A missile test announced by Iran over the weekend was an apparent violation of a U.N. Security Council resolution.
Critics of the Iran nuclear accord don't appear to have enough votes to override Barack Obama's veto.
The U.S. is the largest contributor to the IAEA and funds around a quarter of its annual budget.
At Wednesday's hearing Senators contemplated war and accused administration officials of capitulating.
The Wall Street Journal reports that some U.S. officials hope the move will smooth relations with Israel following the Iran nuclear deal.
U.S. Secretary of State John Kerry will meet Russian President Vladimir Putin in Sochi, Russia, on Tuesday to discuss Ukraine and other issues, the United States said on Monday.
New cartoon from Obama administration takes swipe at Netanyahu's criticism of nuclear agreement.
Many details must still be hammered out, including the pace and extent of sanctions removal.
The Israeli prime minister will today convene his security cabinet to discuss the deal.
Netanyahu has not yet publicly commented on the matter.
Israeli PM tells cabinet of a "Iran-Lausanne-Yemen axis" threatening humanity.
Israeli PM speaks of Iranian presence in Gaza, Lebanon and Golan Heights.
Israeli PM to deliver controversial address on Iranian nuclear programme to U.S. Congress.
Ayatollah Ali Khamenei's statement underlines the gap between Tehran and world powers as they hold talks on a nuclear deal.