Demonstrators have set themselves on fire to protest against the arrests
The Paris appeals court has delayed until Wednesday a ruling on whether 11 Iranian exiles under investigation for terrorist offences should remain in jail.
The members of the People's Mujahedeen (MOK) - including the group's symbolic leader, Maryam Rajavi - have been in preventive detention since 17 June.
They were among 160 people arrested in a series of raids near Paris, ordered by France's top anti-terrorist judge Jean-Louis Bruguiere. Most suspects were later released.
The MOK is an Iranian opposition group designated as a terrorist organisation by the United States, the European Union and the Iranian Government.
The raids sparked a series of demonstrations in Paris and across Europe.
Ten protesters set themselves on fire, two of whom have since died.
A total of 17 MOK members have been placed under judicial investigation - the first step toward formal criminal charges - for alleged links to a terrorist organisation
and for funding terrorist activity.
Six of those being investigated have been released on bail.
French officials in Paris have accused MOK militants of using France as a base to carry out attacks against Iranian interests in Europe.
Dozens of supporters are staging a hunger strike at the headquarters of the National Council of Resistance of Iran, the MOK's political front, near Paris.
Iran has welcomed France's actions against the group, which seeks the overthrow of the Islamic regime.
The group's military wing was disarmed by occupying US forces in Iraq in May.
Maryam Rajavi is the wife of the group's military leader, Massoud Rajavi.