"There are no problems with this [S-300] contract," Mehdi Safari said at the end of his visit to Moscow.
He offered no specifics about the contract's implementation, but dismissed concerns voiced by a number of countries over possible S-300 deliveries to Iran.
"After all, these are purely defensive weapons, and any country has the right to buy them. I believe this could only worry those states that have plans to attack others," he said.
A Russian arms export official said last month Iran had not yet received any S-300 air defense systems.
Iranian media, citing senior security officials, have repeatedly reported that Russia has started delivering elements of the advanced version of the S-300 missile to Tehran under a 2007 contract.
The latest version of the S-300 family is the S-300PMU2 Favorit, which has a range of up to 195 kilometers (about 120 miles) and can intercept aircraft and ballistic missiles at altitudes from 10 meters to 27 kilometers.
It is considered one of the world's most effective all-altitude regional air defense systems, comparable in performance to the U.S. MIM-104 Patriot system.
Iran recently took delivery of 29 Russian-made Tor-M1 air defense missile systems under a $700-million contract signed in late 2005. Russia has also trained Iranian Tor-M1 specialists, including radar operators and crew commanders. The S-300 system is significantly superior to the Tor-M1.