The NFL has threatened to hand down significant punishment to any players or teams involved in fights before or during games.

In a memo obtained Sunday by ESPN, the NFL told teams that fighting "is irreconcilable" with the league's values and "is never acceptable." The memo, sent Wednesday to top executives and head coaches of all 32 teams, also reiterated the league's warmup rules and outlined potential discipline.

Any players or club personnel who fight before or during a game are subject to ejection, suspension and/or "significant fine," according to the memo.