Scores of people gathered in front of Iran's central bank to protest the rial's plummet to record lows against the U.S. dollar, the BBC reported.
Witnesses said the demonstrators called for the governor of the central bank to step down and chanted anti-government slogans.
Police used tear gas to disperse the protesters, some of them in the process of setting fire to tires and rubbish bins.
The head of Tehran's bazaar unions said shopkeepers were afraid to open their businesses because of the demonstrations.
Iranian President Mahmoud Ahmadinejad has blamed Western sanctions for the fall of the rial, calling it an economic war.
At a news conference Tuesday, Ahmadinejad said the quickly eroding strength of the rial was part of a "psychological war" the United States and others were waging against Iran to pressure the country to cease work on an alleged nuclear weapons program.
The rial hit a new low at 37,000 to the dollar Tuesday, down from 26,900 just five days ago, the Los Angeles Times reported.