If you’re gonna be in Vegas for the big fight … and you’re not at an MGM property … you may be S.O.L. — because MGM honchos are blocking competitors from showing Mayweather vs. Pacquiao … TMZ Sports has learned.

Here’s what we know … MGM has an exclusivity deal which blocks rival hotels on the Vegas Strip from showing the fight — and that includes in-room, in bars, in the casino … anywhere.

Of course, the fight is happening at the MGM Grand on May 2nd — a