The rial rebounded to around 48,220 to the dollar on Wednesday after police cracked down on foreign-exchange offices in Tehran, closing 10 offices and arresting around 100 money changers.
Tehran's Police Chief General Hossein Rahimi said 90 dealers were arrested on Wednesday in an operation coordinated with the central bank.
"The detainees, driven by greed, were attempting to disrupt the market and economic order", Rahimi told the Fars New Agency.More news: Police complaint lodged against internet sensation Priya Prakash Varrier's song
The rial has been hurt by concern about Iran's agreement with world powers to curb its nuclear program in return for the lifting of most worldwide sanctions.
Iran's economic ties with foreign countries could be damaged further if the United States pulls out of the nuclear accord, as U.S. President Donald Trump has threatened to do.
But the rial's drop has accelerated in the past several weeks, posing a challenge for the government, which last month saw nationwide protests against economic hardship and corruption that resulted in 25 deaths.More news: EFF explains why it wants early elections
Iran's government has in recent days repeatedly called on people to refrain from rushing to panic buy hard currencies or follow speculators.
State television broadcast footage of the crackdown."The foreign exchange speculators have been identified", central bank chief Valiollah Seif said, quoted by Iranian media on February 15."We will use all means at our disposal to get out of this situation and restore calm to the market". As the currency has continued to lose value, speculators have sped the process along by betting against the rial's value.
The nuclear deal, which imposed curbs on Iran's nuclear activities in exchange for the lifting of worldwide economic sanctions, had raised hopes in Iran that the rial might strengthen back to levels that prevailed before global sanctions were imposed in 2012.More news: US Vice-President Pence suggests Washington ready to talk to N. Korea
But analysts say the fall in Iranian interest rates since September has also stoked the currency's decline by making investments in Iranian bonds and bank deposits less attractive to investors.