NFL Coach Aaron Kromer -- Pleads NOT GUILTY ... In Alleged Kid Beatdown

Buffalo Bills lineman coach Aaron Kromer just plead NOT GUILTY to beating up a young boy at a Florida beach earlier this month.

As we previously reported, Kromer was arrested for allegedly confronting a group of kids at a beach and accusing them of taking his beach chairs.

Kromer allegedly pushed one of the kids to the ground and punched him in the face -- and then threatened to kill their families if they told anyone about the incident.

Kromer and his son were charged with misdemeanor battery. His son also plead not guilty.