If you needed a reminder that fans are not always priority No. 1 -- turn to Russell Crowe -- cause the guy was absolutely not having it outside his Paris hotel.

Check out the clip ... Russell puts autograph hunters firmly back in their lane after the crowd started edging way too close for comfort -- barking out, "Stay where you are, don’t f***in push in on me. I’ll come to you. Give everyone space."

If that warning somehow wasn’t crystal clear ... he followed it up with a pretty simple policy: "As soon as somebody is a d***, I’m gone. We clear?"

Spoiler alert -- this wasn’t one of those celeb moments where everyone laughs and Russell suddenly starts happily signing away. Nope ... he still looked fully checked out, and things got extra awkward when one fan tried asking for a special sign and got flat-out rejected.

Moral of the story? If you get a little outta hand during a celeb meet-and-greet ... don’t act shocked when the star starts acting full gladiator!