The US state department has imposed sanctions on arms firms from Russia, North Korea, India and Cuba for allegedly supplying equipment to Iran.
It said they had broken US laws banning the sale to Tehran of equipment capable of helping the development of weapons of mass destruction.
The sanctions stop US firms working with affected companies - which include Russian aircraft manufacturer Sukhoi.
Russia's foreign ministry condemned the decision as "clearly illegitimate".
Moscow last year signed a deal worth $700m (£380m) to supply surface-to-air missiles to Iran.
Sukhoi has denied having any contracts with Tehran and company chairman Alexander Klementev told Russian radio station Moscow Echo that it had delivered nothing to Iran for at least six years.
The US sanctions were ordered under the 2000 Iran Non-proliferation Act.
A state department official, speaking on condition of anonymity, said the sanctions were imposed after the US obtained "credible information" that the companies had transferred equipment or materials to Iran since 1 January 1999.
"The sanctions apply to the specific entities and their successors, sub-units or subsidiaries and not to their respective countries or governments," the official told Reuters news agency.
Russia's foreign ministry responded by saying that the sanctions were "a clearly illegitimate attempt to make foreign companies work by internal American rules".
In May, Russian Defence Minister Sergei Ivanov confirmed that the deal to supply up to 30 Tor-M1 surface-to-air missile systems to Iran still stands.
Along with Sukhoi, Russian state arms exporter Rosoboronexport has been put under the US sanctions.
The two Indian companies are Balaji Amines Ltd and Prachi Poly Products Ltd, both chemical manufacturers.
The North Korean companies are Korean Mining and Industrial Development Corporation and Korea Pugang Trading Corporation, and the Cuban company is the Centre for Genetic Engineering and Biotechnology.
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