Jason Momoa -- I'm Retiring From Slap Battles

Don't expect to see Jason Momoa slap-battling anymore random dudes at bars ... 'cause the "Game of Thrones" actor says he's hanging up his mitts for good.

Momoa was catching a flight out of LAX when we asked about the video that went viral this week of his dominating slap sesh ... and Khal Drago told us that was his final battle.

Momoa says the dumbass in the video who challenged him was a friend -- and after the battle the guy's hands healed quickly. Why do we think Jason's friend would have a different opinion?

Oh, yeah ... because we've seen the video.