Among potential targets were said to have been government spokesman Christophe Castaner and radical left leader Jean-Luc Mélenchon.
The mosques in the suburbs of Paris were closed by France's Interior Ministry under emergency legislation passed after recent terror attacks.
News came after French PM said he would consider temporary ban on foreign financing of mosques, urging 'new model' for relations with Islam.
The mosques, including one raided on Wednesday when police said a firearm was found, are the first to by closed for reasons of 'radicalisation'.
Dalil Boubakeur said current number of 2,200 mosques in France did not adequately represent Europe’s largest Muslim community.