France has frozen some Iranian assets after an alleged conspiracy to bomb a Paris meeting where the star speaker was Rudy Giuliani, Donald Trump's high profile legal adviser.

 In July, an Iranian diplomat was been charged with conspiracy to commit murder. German federal prosecutors said  the Vienna-based diplomat Assadollah Assadi was suspected of contracting a couple in Belgium to attack the gathering of an exiled Iranian opposition group. They said he was suspected of having given the couple a device containing 500 grams of the explosive TATP.

President Trump's lawyer Rudy Giuliani and several former European and Arab ministers were among those attending the rally of the Paris-based National Council of Resistance of Iran (NCRI).

Now, the French government has  pointed the blame for the foiled  terror plot at Tehran. French diplomats believe that Iran's intelligence ministry, which is controlled by Ayatollah Ali Khamenei, the supreme leader, ordered the attack.

"This extremely serious act envisaged on our territory could not go without a response," France's interior, foreign and economy minister's said in a joint statement. "In taking this decision, France underlines its determination to fight against terrorism in all its forms, particularly on its own territory."

The two suspects in Belgium were intercepted with 500 grams of TATP, a home-made explosive produced of easily available chemicals, as well as a detonation device found in their car, according to the Belgian prosecutor and the intelligence services. The 38-year-old man and a 33-year-old woman, identified only as Amir S. and Nasimeh N., were charged with attempted terrorist murder and preparation of a terrorist act.

Mossad, Israel's intelligence serivce, was also involved in thwarting the attack, according to reports.

France seized assets belonging to Tehran's intelligence services, the arrested diplomat and Saeid Hashemi Moghadam, the deputy minister and director general of intelligence.

Rudy Giuliani Rudy Giuliani, former Mayor of New York City, delivers his speech as he attends the National Council of Resistance of Iran (NCRI), meeting in Villepinte, near Paris, France, June 30, 2018. Photo: REUTERS/Regis Duvignau

NCRI is an umbrella bloc of opposition groups in exile that seek an end to Shi'ite Muslim clerical rule in Iran.

Its meeting, which attracted a crowd of thousands, took place  in Villepinte, just outside of Paris, a three-hour drive from Brussels.

NCRI, also known by its Farsi name Mujahideen-e-Khalq, was once listed as a terrorist organization by the United States and the European Union but is no longer.