The Iranian rial collapsed last week, sending protesters into the streets of Tehran. At its low point, it took more than 37,000 rials to buy one U.S. dollar. Tehran restricted transactions in foreign currency to the Central Bank this week to add value to the rial, The New York Times reported.
U.S. and European sanctions target the Iranian energy sector. White House spokesman Jay Carney described the sanctions as the "most intense" in history.
"We have diplomatic isolation and international isolation that's unprecedented in history and it's having a profound impact on both the Iranian economy and the Iranian regime's internal political structure," he said.
Republican presidential nominee Mitt Romney, in a foreign policy address at the Virginia Military Institute, said he'd take a stronger line with Iran if elected in November.
"I will put the leaders of Iran on notice that the United States and our friends and allies will prevent them from acquiring nuclear weapons capability," he said. "I will not hesitate to impose new sanctions on Iran and will tighten the sanctions we currently have."
Iranian President Mahmoud Ahmadinejad blamed sanctions for his country's economic woes. The report from the Times notes that Iranian lawmakers voted to question Ahmadinejad over his economic policies.