The single-rate system failed to stabilise the rial in June, when the currency sank to around IRR 90,00 per dollar in black market trade.
Iran has formally opened a secondary market for hard currency, abandoning three months effort to dictate a single exchange rate for the rial against the dollar as the threat of US sanctions pressures the currency, reported Reuters.
The new market will cater to small exporters and importers from the private sector.
Central bank officials believe the secondary market will allow exchange rates to fluctuate freely.
The development is an attempt by authorities to halt a plunge in the rial to record lows against the dollar that was fuelled by US President Donald Trump's decision to withdraw from world powers' 2015 deal with Iran on its nuclear programme and intention to slap Iran with more sanctions later this year.