Justin Gaethje Says He'll Knock Out Conor McGregor In Ireland

Conor McGregor appears unretired from fighting ... and Justin Gaethje tells TMZ Sports he BADLY wants to be locked in a steel cage with The Notorious.

But, does Conor want to fight him? Gaethje says nah, doubt it.

"[Conor's] a warrior. I know that it would intrigue him for sure. But, I also think his mind would be like, 'no, thank you.'"

"He can't take my leg kicks. If I wanted to wrestle him, I could wrestle him all day. And, I could knock him out. The last thing he needs to be is f**king on his back reaching for the sky and I will, I could do that to him."

Gaethje's coming off a crazy impressive performance ... he starched Edson Barboza -- one of the scariest dudes in the UFC -- with a vicious right hook in the 1st round last weekend.

Earlier in the week, JG -- the 5th ranked UFC lightweight -- told us he wanted the Holloway-Poirier winner and then Khabib ... but when he was in the TMZ offices on Thursday, clearly things done changed.

"I wanna fight [Conor]. I wanna fight him in Ireland. I know it's not gonna happen in Ireland, but that's my dream. To go over there and be in that sorta chaos. That's what f**king wakes me up every day."

"I'm going out there. I'm gonna stand. I'm gonna stand, I'm gonna knock him out. If he wants to retire, I can help him on his way out."

Conor-Gaethje would be a sick fight ... both guys have great power in their hands and ain't afraid to stand toe-to-toe and mix it up.