T.I.: NYC Shooting Ruins Graduation Gig ... He's Too Gangsta!

T.I.'s wallet got caught in the crossfire of that NYC shooting -- a huge high school graduation party thinks he's damaged goods after the violent incident ... and organizers are demanding a $55k refund.

Tip was set to perform a concert in South Florida for grads from multiple high schools on June 11. The contract was signed and promoters had sent him $55,000 to retain his services -- but then the shootout happened.

TMZ has learned promoters fired off a legal notice saying, due to the shooting, "the quality of the Talents services is not satisfactory to our Client." They added ... the event was marketed "as a safe environment for the students."

Translation: We're worried kids will get shot if you do this show.

To be fair -- T.I. and his crew had nothing to do with the NYC incident. He hadn't even taken the stage when the shots rang out.