The United States on Monday ratcheted up its efforts to isolate Iran for its suspected nuclear weapons program, targeting Tehran with currency and auto-sector sanctions, Reusters reported.
President Barack Obama imposed sanctions on foreign financial institutions that conduct or facilitate significant transactions in the Iranian rial currency.
In an executive order, the president also approved sanctions against people who do business with Iran's auto sector, which the White House said was a major source of revenue for Tehran.
The United States and Western powers have imposed a series of economic sanctions aimed at pressuring Iran into halting what they say is a drive to build a nuclear weapon. Tehran says its nuclear program is purely for generating power and for medical devices.
Last week, the United States blacklisted eight companies in Iran's petrochemical industry.
"We hold the door open to a diplomatic solution that allows Iran to rejoin the community of nations if they meet their obligations," White House press secretary Jay Carney said in a statement. "However, Iran must understand that time is not unlimited. If the Iranian government continues down its current path, there should be no doubt that the United States and our partners will continue to impose increasing consequences."
The sanctions imposed on the rial on Monday included a ban on maintaining significant accounts outside Iran denominated in that currency. It is the first time that trade in the rial has been targeted directly for sanctions, the White House said.