Government spokesman Gholamhossein Elham accused Israel of threatening global peace but reiterated Tehran's publicly stated view that it was not in a position to attack Iran.
Western powers accuse Iran, the world's fourth-largest oil exporter, of seeking the atom bomb under the cover of a civilian nuclear program. Iran denies the charge, saying it only wants to master atomic technology in order to generate electricity.
The United States and Israel have not ruled out military action if the dispute cannot be settled through diplomacy.
During a visit to Damascus on Thursday, French President Nicolas Sarkozy said Iran was "taking a major risk in continuing the process to obtain a military nuclear capacity." He added, "One day... we could find one morning that Israel has struck."
Iran's state broadcaster IRIB quoted Elham, the government spokesman, as saying in response to Sarkozy's statement, "These threats are because of weakness... and it reflects the reality and the war-seeking nature of the Zionist regime."
Elham added, "This regime is not big enough and does not have the capacity to want to think about a war with Iran."
He said Israel "uses every chance to threaten global security and peace."
The UN Security Council has imposed three rounds of sanctions against Iran over its failure to heed calls to suspend uranium enrichment, a process that can produce fuel for power plants or nuclear weapons if refined further.
Israel, long assumed to have its own atomic arsenal, has sworn to prevent Iran from emerging as a nuclear-armed power.
Speculation about a possible attack on Iran's nuclear facilities has risen since Israel staged an air force exercise in June which was reported to be a simulation of a strike against Iran. Iran says it would hit back if attacked.