Tehran says the West should withdraw its "illogical" demand that Iran halt production of uranium enriched to 20 percent.
Foreign Ministry spokesman Ramin Mehmanparast told reporters on Tuesday as saying that Iran has a right to produce nuclear fuel for peaceful purposes.
The West is concerned that uranium enriched to 20 percent, used for fuel in Iran's medical reactor, could quickly be turned into more highly enriched weapons-grade material.
However, the Iranian official welcomed negotiations between Tehran and the West, expressing hope the next round of talks in Moscow will bring two sides closer.
Iran and six world powers held talks in Baghdad last week on Tehran's nuclear ambitions. The West suspects Iran is trying to develop weapons, a charge Iran denies.