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.
Bottom line, GGG realizes this is the fight the fans want, and is determined to put on the big drama show one way or another.