Tehran caused a flap on international markets earlier this year after its central bank governor was quoted as saying the country was repatriating dollars held in foreign accounts as pressure mounted on Iran's nuclear programme.
Those remarks were swiftly retracted.
But on Monday, Davoud Danesh-Jafari, the finance minister, told a news conference: "There have been symbolic acts of late and America has restricted Iran's dollar-based transactions with the outside world through seven or eight financial institutions."
He said that the institutions were either US-owned or "influenced by the Zionists".
"But this will not cause any trouble in the end because when dollar-based transactions get restricted, we can use other currencies and that would be against US interests," he said.
Iran's holdings in foreign countries are unclear but are considerably more than $25 billion. All earnings from crude exports above a budgeted level are held abroad.
It was not immediately clear to which institutions the minister was referring.
Iran has been reported to the UN Security Council for possible sanctions after failing to convince the UN's nuclear watchdog that its programme was exclusively for generating electricity.
Washington threatens sanctions against countries doing business with Iran, which it accuses of seeking nuclear arms, funding anti-Israeli militias and fomenting attacks on US troops in Iraq. Tehran denies the claims.
Iran's central bank has said Swiss bank UBS severed relations with Iran because of the influence of its US shareholders.
Credit Suisse has said it will not enter into new business in Iran. Dutch bank ABN Amro said in December it would pay an $80 million penalty for failing to comply with US anti-money laundering laws over Iran.
"But this will not cause any trouble in the end because when dollar-based transactions get restricted, we can use other currencies and that would be against US interests"
Iranian finance minister
The bank said its employees developed procedures to send payments to the bank's New York clearing centre on behalf of Iranian clients, failing to include information on where the money came from to avoid it being blocked.
Despite the problems with UBS, Credit Suisse and ABN Amro, the world's fourth-biggest oil exporter says that it has good relations with other European and Japanese lenders.
HSBC, BNP Paribas, Deutsche Bank, Commerzbank, Standard Chartered and the Royal Bank of Scotland have funded Iranian projects.
Iran's manufacturing sector, particularly car making and shipbuilding, is growing too quicky for domestic banks to cope, and economic analysts say Iran would be vulnerable to sanctions on foreign financing.