Cops are so livid over the way they say Jaxson Hayes fought them during his arrest last month ... they're now strongly urging NBA commissioner Adam Silver to take action against the Pelicans star.

It's all spelled out in a letter, obtained by TMZ Sports, written by the Los Angeles Police Protective League -- a police union representing 9,000 rank and file LAPD officers -- to Silver and New Orleans Pelicans owner Gayle Benson.

In the note -- which is four pages in length -- the police union says 6'11, 220-pound Hayes became combative on July 27 after they responded to a domestic disturbance call involving the hooper.

Law enforcement says Hayes refused orders, hurled the n-word at officers, and pushed one cop so hard into the wall, the basketball player injured the "much physically smaller" man.