The US has imposed economic sanctions on Iran’s national airline, saying Iran Air had supported the Iranian military.
In a statement, the treasury department also said the airline had provided “material support and services” to the Iranian Revolutionary Guard.
It said the paramilitary group supported terrorism and committed human rights abuses against protesters.
The US accuses Iran of aiming to develop nuclear weapons. Tehran says its programme is wholly peaceful.
In addition, the US treasury department accused Iranian port company Tidewater Middle East Company of the Revolutionary Guard Corp of exporting arms and military equipment from the seven ports it operates in the country.