Yes, you will have to re-enter security. You will arrive in the Delta terminal (most likely term 2, possibly 3 though they are both connected) then you will need to walk across the street to get on the airtrain and go to Terminal 1 for Air france. Then you will re-enter security from there. http://www.airportterminalmaps.com/JFK-terminal-map.html this site has a map of the JFK terminals. I hope this helped and Have a great trip!
airfrance flight