MOSCOW (Reuters) - The Kremlin on Tuesday branded U.S. sanctions against two leading Russian arms exporters "an unfriendly act" and warned they could rebound on U.S.-Russia relations.

The United States announced sanctions on Friday on seven firms from Russia, India, North Korea and Cuba for selling items to Iran.

The sanctions were imposed on Russian state export agency Rosoboronexport -- headed by a close friend of President Vladimir Putin -- and state-owned warplane maker Sukhoi.

"This looks like unfair competition. It was an unfriendly act towards Russia and it was not done in a spirit of cooperation," Kremlin spokesman Dmitry Peskov said.

"If we are to speak about possible consequences of this act for bilateral relations, of course it has not contributed to a further strengthening of the partnership. Among other things we can not rule out further negative consequences for this relationship," he said.

Last year Russia signed a contract to sell Tehran TOR-M1 ground-to-air missile systems and to modernize Iran's Russian fighters, bombers and military helicopters.

Russian media said the sanctions were triggered by Rosoboronexport's announcement last month of $3 billion in arms deals with Venezuela, tied up in a visit to Russia last week by President Hugo Chavez.

Rosoboronexport has sought to play down the impact of the U.S. sanctions.

The Indian Foreign Ministry also said in a statement on Monday that U.S. sanctions against two of its firms for selling what Washington says are restricted items to Iran were unjustified as they had not violated any domestic laws or New Delhi's global obligations.