"I'm retired, dude," Manziel told TMZ Sports outside of Saddle Ranch in L.A. on Friday.

Manziel's only 27 years old -- and brought solid TV ratings to the CFL during his 2018/2019 comeback ... begging the question, would The Rock's XFL make a run at Johnny to try and boost interest?

"Listen, anything The Rock touches is gonna be gold as always," Manziel says ... "But, I think football is a little bit behind me."

"I'm just trying do to other things in life that make me happy. That's it."

To prove his point, Manziel fired up a cigarette -- and told us straight up, "There's more to life than just ball."

The former Heisman Trophy winner and 2015 1st-round NFL Draft pick is not completely closing the door on a comeback ... saying he still trains and works out -- but it's highly unlikely.

"You never say never, I'm still an athletic guy ... but at the end of the day, let's see where the rest of life takes me and we’ll go from there."

"Football for me is not at the forefront of my mind. It's just chillin’ and being one of the bros."

Manziel also talked about his beef with sports business reporter Darren Rovell ... and explained why it's a long-running issue "that'll get settled up one day."

Oh, and as for why Manziel is out in L.A. during a global pandemic without a mask?

"COVID doesn’t wanna see me at the end of the day," Manziel joked ... "dude, I do worse things on the weekend."