EXCLUSIVE

Nashville Predators star Mike Ribeiro is being sued by his former nanny -- who claims the NHL star assaulted her back in 2012 ... but Ribeiro says she's making the whole thing up.

In the lawsuit, obtained by TMZ Sports, Ribeiro's accuser doesn't go into detail about the alleged incident ... only claiming she suffered unspecified injuries at the hands of the 35-year-old All-Star.

The woman also claims ... after the alleged incident, Mike's wife verbally attacked her. She's suing both Mike and his wife for more than $1 MILLION.

But the Riberios say the whole thing is BS -- with their lawyer telling TMZ Sports, "My clients strongly deny these allegations."