The incident happened Monday in the second quarter of Sacramento's 119-96 loss to Dallas when Cousins was fighting for position under the basket with the Mavericks' O.J. Mayo.
The Kings center sent a closed fist behind him, striking Mayo in the groin. Cousins said the action was unintentional, but the NBA disagreed, suspending him for one game -- Wednesday's contest at Milwaukee.
Sacramento's leading scorer also received a two-game sanction following a Nov. 9 game when he got into an heated exchange with San Antonio Spurs announcer and former player Sean Elliott.
Cousins is averaging 17.2 points and 9.9 rebounds per game.