Iranian Revolutionary Guards at a military parade in Tehran
The US has imposed sanctions on six people and three companies it says have ties to Iran's powerful Revolutionary Guard Corps (IRGC).
Treasury Secretary Steven Mnuchin said the penalties targeted those who had funnelled millions of dollars to the group, funding its "malign activity".
Iran's central bank was also accused of helping the IRGC to access US dollars.
The Treasury Department did not name the sanctioned individuals, but said they were all Iranian.
The move - which was carried out in conjunction with the United Arab Emirates (UAE) - prohibits US individuals and entities from doing business with them.
"The Iranian regime and its Central Bank have abused access to entities in the UAE to acquire US dollars to fund the (IRGC's) malign activities, including to fund and arm its regional proxy groups," Mr Mnuchin said in a statement.
"We are intent on cutting off IRGC revenue streams wherever their source and whatever their destination," he added.
What is the Revolutionary Guard?
The IRGC was set up in 1979 to defend Iran's Islamic system and is a major military, political and economic force in the country. The sanctions specifically target its overseas operations arm, the Quds Force.
President Donald Trump has labelled the group a "corrupt terror force and militia" and, in October, he hit them with sanctions.
The latest penalties come just two days after Mr Trump pulled the US out of the Iran nuclear deal and pledged to ramp up pressure on Tehran.
The 2015 agreement curbed Iran's nuclear activities in return for the lifting of UN, US and EU sanctions.
Mr Trump's decision to abandon the deal was described as a "mistake" by Iran's supreme leader, Ayatollah Ali Khamenei.