Since 2007, Iran has received 85 percent of its oil income in currencies other than the U.S. dollar, Iran's English-language Press TV reported on its web site.
"Iran has considerably reduced the total of U.S. dollars in its currency basket," Bahmani said.
Press TV did not give additional detail on how Iran has benefited from reducing the role of the U.S. unit in its transactions.
Iran, the world's fifth-largest oil exporter, says a weak U.S. currency is eroding its purchasing power. The Islamic state is under U.S. and U.N. sanctions over its disputed nuclear programme.
Iranian President Mahmoud Ahmadinejad has called the U.S. currency a "worthless piece of paper".
At a 2007 heads of state summit of the Organization of the Petroleum Exporting Countries (OPEC), Iran suggested oil should be priced in a basket of currencies rather than dollars, but it failed to win over other member states except Venezuela.
The Iranian central bank has said it has been diversifying its reserves away from the dollar.