The economic sanctions on Rosoboronexport were imposed in connection with the alleged proliferation of weapons of mass destruction.
"The United States introduced these sanctions without any basis in international law. We will take that into account in our relations with the United States," Foreign Minster Sergei Lavrov said.
Sanctions were also imposed on the same grounds against Venezuela, China, North and South Korea, the United Arab Emirates, Sudan, and Syria, as well as the Iranian Islamic Revolutionary Guards.
Lavrov said that the sanctions would not force Russia to make concessions on Iran's nuclear program.
"If some people in Washington think that this would make Russia more amenable to the U.S. approaches with regard to the Iranian nuclear problem, they are wrong," Lavrov said.
The sanctions are valid for two years and bar any U.S. aid, contracts or arms sales to the blacklisted entities.
The order was signed on October 16 and came into effect on Thursday.
A Rosoboronexport representative called the sanctions a "manifestation of unethical competition."
"We view the imposition of sanctions with regard to the sole Russian facilitator of arms sales as a manifestation of unethical competition," said Vyacheslav Davydenko.
In July and December 2006, the United States also imposed sanctions on Rosoboronexport for allegedly passing on equipment to Iran that could be used to develop weapons of mass destruction.
