French intelligence concluded that Iran's intelligence ministry, which is controlled by Supreme Leader Ayatollah Ali Khamenei, ordered a foiled attack on an exiled Iranian opposition group's rally near Paris in June, a French diplomatic source said.

"Behind all this was a long, meticulous and detailed investigation by our (intelligence) services that enabled us to reach the conclusion, without any doubt, that responsibility fell on the intelligence ministry," the source said.

The source added that deputy minister and director general of intelligence Saeid Hashemi Moghadam had ordered the attack.

France seized the financial assets of two Iranian individuals as well as some belonging to Iran's intelligence services, according to the government journal published on Tuesday.

France said a foiled plot to bomb an exiled Iranian opposition group's rally outside Paris on June 30 is linked to the asset freezing. The plot was reportedly thanks to crucial intelligence information provided by Israel's Mossad espionage agency.

Also Tuesday, elite police swooped on a Muslim center and several residences in northern France.

France told its diplomats and Foreign Ministry officials in August to postpone indefinitely all non-essential travel to Iran, citing a foiled bomb plot and a hardening of Tehran’s attitude toward France, according to an internal memo seen by Reuters.

The Mossad gave Germany, France and Belgium crucial intelligence information about the attack, which led to arrests of a cell headed by an Iranian diplomat.

France had warned Tehran to expect a robust response after an Iranian diplomat was arrested in Germany suspected of involvement in the plot, which targeted the Paris-based National Council of Resistance of Iran (NCRI).

U.S. President Donald Trump's lawyer, Rudy Giuliani, and several former European and Arab ministers attended the rally in Villepinte.

"An attempted attack in Villepinte was foiled on June 30. An incident of such gravity on our national territory could not go unpunished," said a joint statement by the foreign, interior and economy ministries.

The asset freezes targeted two individuals identified as Assadollah Asadi and Saeid Hashemi Moghadam, the French statement said. A unit within the Iranian intelligence services was also targetted.

Any hardening of relations with France could have wider implications for Iran. France has been one of the strongest advocates of salvaging a 2015 nuclear deal between Iran and world powers, which U.S. President Donald Trump pulled out of in May.