Frankie Edgar says it would be ridiculous if Cris Cyborg gets sued for punching Angela Magana in the face ... telling TMZ Sports Magana should've seen it comin' when she ran her mouth.

We spoke with Edgar about Magana's plans to pursue legal action ... and The Answer clearly disagrees with the idea, saying "it's kinda crazy to me."

"I don't know how a fighter can press charges for getting hit," Edgar tells us. "Especially if you run your mouth."

"I'd never sue someone over a fight."