Barnes, 32, was arrested in Manhattan Beach in July on suspicion of threatening a public official, a felony. Barnes was arrested after an officer who was aware he had an outstanding warrant for a misdemeanor traffic violation approached him on foot.
But the Los Angeles County district attorney's office chose to file a misdemeanor and it agreed to a deal on the lesser charge.
The Clippers open the regular season Wednesday at home against the Memphis Grizzlies and if Barnes is physically fit and eligible to play, he would be suspended for that game.
Barnes signed in the offseason with the Clippers after playing the last two seasons with the Lakers.