Witnesses in Iran say riot police fought with protesters Wednesday marching against the plunge in the nation's currency, the rial.
Shopkeepers in Tehran's main bazaar shut down their stalls and police reportedly have arrested illegal street currency changers.
Iranian President Mahmoud Ahmadinejad has rejected growing domestic criticism of his policies as the rial slumped to record lows against the dollar this week.
Street traders said the rial traded as low as 39,000 to the dollar on the black market Tuesday before recovering slightly. Last week it traded at about 24,000 to the dollar.
Ahmadinejad blames the plunge on what he called "psychological pressure" by Iran's enemies.
U.S. Secretary of State Hillary Clinton said Wednesday that international sanctions on Iran over its suspected nuclear weapons program have had an impact. But she said Iranian leaders and their decisions that have nothing to do with sanctions are responsible for Iran's economic problems.
She said the sanctions could be remedied in short order if Iran is willing to work sincerely with the international community on its nuclear program.
Iran's Fars news agency quoted Parliament Speaker Ali Larijani this week as saying he believes 80 percent of the country's economic problems are linked to government mismanagement.
Some information for this report was provided by AP, AFP and Reuters.