It is not compulsory but it will be very helpful to you for Post graduate studies in France .. may be they will provide PG courses in English language also ..it is better that you learn French language.

For learning French you can take admission in one of the following institutes :
S.N Career Education, Vastrapur, Ahmedabad
NAM Institute of Professional Studies, South Ex 1, Delhi
Foreign Language Institute, H.S.R Layout, Bangalore
Coral9 Consulting, Karve Nagar, Pune
Institute For Inspiration & Self Development, Salt Lake City, Kolkata