Paris isn't a cruise port, but is served by the port of Le Havre. Added up, the cruise port of Le Havre functions as the port of embarkation for just twenty cruises anually from both MSC and Princess to Europe.
Cruises scheduled from Paris during the the peak season of summer are considerably more expensive than the the low season of fall. On average Paris is rather expensive compared to other ports. Check the diagram below for the monthly average cost per day (cruises only depart from Paris between May and October).