Aldon Smith -- Won't Be Charged with Felony ... In LAX Bomb Arrest

San Francisco 49ers superstar Aldon Smith will NOT be charged with a felony for allegedly telling TSA agents he had a bomb on his person at LAX earlier this month ... TMZ Sports has learned.

The L.A. County District Attorney's Office tells us ... the case has been kicked down to the L.A. City Attorney's Office for possible misdemeanor prosecution ...where the stakes are a lot lower.

We broke the story ... Smith was arrested on April 13th -- and cops say he was "belligerent and uncooperative" during the arrest.

The City Attorney is deciding whether to charge him with a crime of falsely reporting a bomb threat.

Stay tuned ...