Buffer -- the voice of the UFC -- says he's very close with Hollywood powerhouse Nick Cassavetes (directed "The Notebook," "Alpha Dog," "John Q.") ... and he's not turning his back on Rousey after the beating she took from Holly Holm.
Cassavetes also happens to be directing Ronda's next movie -- "Road House" -- and says he's pumped about having her star the film.
It's a pretty big endorsement for Rousey ... who's been a little "off" ever since the loss ... leading some people to question if she'll still be able to slay at the box office.
And get this ... Bruce says he MIGHT get a role in the flick, too.
Check out the clip ...