Gennady Golovkin Still Wants Canelo Rematch, Gunning For September

Gennady Golovkin is NOT giving up on a second mega-fight with Canelo Alvarez, despite his positive PED test ... and now has his sights set on a September 15 rematch.

TMZ Sports spoke with GGG's promoter, Tom Loeffler, who tells us Gennady is "100%" committed to getting the Canelo rematch on the calendar ... explaining "that's the main focus for GGG."

Loeffler says Golovkin is still committed to fighting on May 5 ... and his team is searching for the best possible opponent to step in for Canelo.

As we previously reported, Canelo withdrew from the rematch Tuesday after testing positive for Clenbuterol, a banned substance that helps athletes cut fat while maintaining muscle mass.

Loeffler says GGG is "frustrated" with Canelo -- and added that's there's a lot of bad blood between the guys.