Warner Brothers announced last week that Affleck would play the superhero in the sequel to "Man of Steel." Shortly thereafter, the "Argo" star received a barrage of tweets expressing their frustration with the decision.
At the VMAs on Sunday, Gordon-Levitt was asked what he thought about the new Dark Knight.
"That's gonna be great," Gordon-Levitt said. When pushed to elaborate, he said, "Oh, but it's gonna be good. I think it's gonna be good."
Gordon-Levitt was rumored to play the superhero for the Superman vs. Batman movie, and has hinted that he might be the next one after this film.
Affleck will star opposite Bryan Cranston, who will play Superman's arch nemesis Lex Luthor.