Harry Styles is taking a stand against Nashville bootleggers ahead of 2 big concerts he has coming up in Music City.

Live Nation, Harry's tour promoter, just filed a lawsuit against anonymous makers of unauthorized Styles concert merch. Harry's playing at the legendary Grand Ole Opry next week ... and then he'll be back at Nashville's Bridgestone Arena next June.

Live Nation says it has knowledge the bootleggers are licking their chops for these gigs, and it's suing to get a court order for cops to seize all the counterfeit merch and destroy it.