The announcement is a slap in the face to Russia, which signed a contract with the Islamic Republic in 2007 to sell the advanced missile system, but delayed the sale after the United Nations imposed a fourth round of sanctions on Iran earlier this year.
The agency which is affiliated with Iran's Revolutionary Guards, said Tehran purchased two of the advanced missiles from Belarus, but failed to reveal the source of the other two missiles.
The S-300 anti-aircraft missile defense system is capable of shooting down aircraft, cruise missiles and ballistic missile warheads at ranges of more than 90 miles at altitudes of about 90,000 feet .
The agency said the Hezbollah al-Manar satellite station first reported on Iran's missile acquisition last year.
The report said Iran intends to start producing missiles similar to the S-300 itself.