Reviled by Tehran, the People's Mujahedeen was founded in 1965 and has been banned in Iran since 1981
Iran has accused an exiled opposition group of orchestrating an alleged plot to bomb one of its own rallies near Paris and said a couple arrested in Belgium were actually members of the group.
Belgium, France and Germany detained six people over the alleged plan to bomb a weekend rally of the People's Mujahedeen of Iran (MEK) in the Paris suburb of Villepinte.
Tehran has dismissed accusations it was behind the plot. In a fresh statement, the foreign ministry said it was the People's Mujahedeen itself that was behind the "scenario."
"Based on the information available, the individuals arrested in Belgium are among the ... notorious and operational elements" of the MEK, the ministry said on its website.
"Relevant Iranian authorities are prepared to offer the necessary cooperation by presenting the required documents and evidence to shed light on the real dimensions of this pre-planned scenario orchestrated by the terrorist group," it said.
French and Belgian authorities said on Monday a Belgian couple of Iranian origin had been arrested in Belgium on suspicion of planning the attack. The others arrested included a Vienna-based Iranian diplomat.
Reviled by Tehran, the People's Mujahedeen was founded in 1965 and has been banned in Iran since 1981.
The rally on Saturday was attended by thousands of people and attracted several US politicians, including former New York mayor Rudy Giuliani, who is now President Donald Trump's personal lawyer.
The announcement of the arrests coincided with the start of a European tour by Iran's President Hassan Rouhani, who is visiting Switzerland and Austria to seek guarantees from European powers over a landmark 2015 nuclear agreement, after the US unilaterally pulled out of the deal in May.
Foreign Minister Mohammad Javad Zarif, who is with Rouhani in Europe, said on Monday the foiled Villepinte attack was a "false flag ploy" to harm Iran and offered his country's help in investigating the matter.
Iran's official IRNA news agency said the foreign ministry had summoned France's ambassador to Tehran, Francois Senemaud, to hear officials "strongly protesting against the activities of the terrorist and hypocritical MEK group in France."
"Extremist terrorist groups should not be allowed to take refuge (in a country) under the pretext of freedom of expression and thus promote their ideology," it said, citing the ministry.
French sources confirmed to AFP that the ambassador had been summoned.
On Tuesday the ultra-conservative Kayhan newspaper criticised the ministry's handling of the case and called for the expulsion of the French ambassador, who is due to step down days after being appointed as President Emmanuel Macron's personal representative for Syria.