In a statement on the official website of its foreign ministry, Iran announced the measure was against the Trump administration's order to impose sanctions on more than two dozen people and companies from the Persian Gulf to China on Friday.
Describing the U.S. sanctions "illegitimate", the statement said, "Iran, in accordance with the principle of reciprocity, will impose sanctions on the pro-extremist terrorist groups in the region and on the persons and companies who help the murderers and the criminal defenders in the region."
"The names of these people and companies will be announced in time," it added. On Friday, the U.S. had unleashed a fresh wave of sanctions on Iran, blacklisting 13 individuals and 12 companies.
The economic penalties are the first official actions taken against Tehran after President Donald Trump's National Security Advisor Michael Flynn said the U.S. was officially "putting Iran on notice" for a ballistic missile test and support for Yemen's Houthi rebels.