Ahmad Khatami, speaking at a Tehran University prayer service to mark the Muslim holiday of Eid al-Adha, also warned world powers that Iran would not be swayed by "bribery" or cowed by threats from its rights to nuclear technology.
He was responding to a resolution adopted on Friday by the International Atomic Energy Agency (IAEA) demanding that Iran halt construction of a new uranium enrichment facility.
Uranium enrichment is the process used to make fuel for nuclear power plants, but when extended it can also produce fissile material for an atomic bomb.
Western powers have long suspected that Iran, despite its fierce denials, is trying to build a nuclear bomb.
Khatami deemed the resolution to be "completely political and not technical in nature," but did not discuss the substance of it.
Addressing the IAEA, he said "it is your obligation, under the law, to provide fuel for the Tehran reactor.
"If you did this, the issue would be closed. If you do not cooperate you should know that the nation … which achieved its rights to technology will also provide fuel for its reactor. It is legal and in accordance with international safeguards."
The IAEA had brokered a deal under which Russia would lead a consortium that would enrich uranium for the Tehran reactor.
Iran, however, has rejected the deal, which would have involved it shipping low-enriched uranium abroad and receiving a more highly enriched version in exchange.
The IAEA has also rebuffed a counterproposal under which the exchange would take place on Iranian soil.
Khatami, who did not specifically address the specifics of the IAEA resolution, said "Islamic Iran has shown to the world over the past 30 years that it will not back down even an inch, whether in regard to its absolute rights or in the face of threats or bribery.
He added, without elaborating: "Of course, Iran will have the option to confront you.
