"(Iran) will not wait for the IAEA meeting on March 6 to resume enrichment," government spokesman Gholam Hossein Elham told reporters.
The United States accuses Iran of seeking to build a nuclear bomb under cover of a peaceful nuclear program. Iran denies this, insisting its program is for the generation of electricity.
Talks postponed
Mr Elham had earlier announced that talks between Iran and Russia aimed at finding a compromise by having Iranian uranium enriched on Russian soil would not go ahead as planned on February 16.
Russia’s Deputy Foreign Minister Sergei Kislyak said he was still expecting an Iranian delegation to visit Moscow for the talks
But Mr Elham told reporters that the talks have been postponed indefinitely and will reconvene at a time of "mutual agreement".
He said the negotiations had been postponed because of the "new situation", a reference to the International Atomic Energy
Agency's decision earlier this month to report Iran's nuclear file to the UN Security Council.
Russia’s plan was an attempt to avoid international objections to Iran's enriching uranium - a process that can also produce material for nuclear weapons.