TNT isn't about to lose its media rights deal with the NBA without a fight ... it just sued the basketball org. -- claiming it has a "contractual right" to continue to broadcast its games going forward.
The media company -- whose parent organization is Warner Bros. Discovery -- filed the lawsuit in New York on Friday ... just days after Adam Silver revealed the NBA is moving on with Amazon Prime Video.
In their suit, TNT officials claim the NBA legally cannot accept Amazon's deal -- as they say they matched the offer to a T.