This is a map from SkyVector with the airspace around Paris:
You can see several major airports like Charles De Gaulle and Le Bourget to the North East and Orly to the South. In the center, there is a region marked LFP-23. This is the restricted airspace you probably had in mind. The French AIP defines it as follows:
LF P 23 PARIS
SFC to 6500ft AMSL
Excluding LF-P 47 BALARD, which retains its status.
CAG/CAM: prohibited penetration, including unmanned aircraft, with the exception of:
- after agreement of the Préfecture de Police de Paris, aircraft on mission of emergency medical service, civil security, gendarmerie, state transport customs and defense for which bypassing is not compatible with the execution of the mission ;
- defence aircraft on air security missions (notification to the Préfecture de Police de Paris as soon as possible) ;
- aircraft that have applied for entry to the police headquarters in Paris at least five working days before the date of the flight and have obtained formal authorization ;
- aircraft authorised by the Paris-Issy-les-Moulineaux Heliport Control Authority (LFPI) which follow departure and arrival procedures published by means of aeronautical information ;
- twin-engine helicopters, in the event of engine failure at the take-off of the Paris-Issy-les-Moulineaux heliport (LFPI) in accordance with the regulations in force ;
- flights authorised in accordance with the procedures described in AIP ENR 1.2 and aeronautical chart 1/100 000 "Itineraires Hélicoptères" in CTR PARIS (appendix of 8 February 1984 decree).
You therefore shouldn't see any commercial aircraft flying in this restricted airspace below 6500 ft AMSL. Above that and outside of the marked region, the restriction does not apply.