DMX -- 'Police Suck D**k!'

DMX says American cops are a bunch of d**k-sucking losers who go after him because he's famous.

X -- who's been busted more times than a cheap watch -- unloaded from the relative safety of Bulgaria, where he was scheduled to perform last weekend.

The rapper only recently regained his right to travel outside the U.S. -- his passport had been yanked because he owed a huge amount in back child support.

But he's gotta come back to the U.S. sometime ... and the cops here ain't gonna like this one bit.