The NFL warned its teams Monday that it will begin levying "significant discipline" to anyone engaging in offensive conduct or contact against game officials, responding to a series of incidents that had grown increasingly worrisome to the NFL Referees Association.

The message was delivered Monday via a memo written by NFL executive vice president Troy Vincent. In the letter, Vincent wrote: "We want to keep our players on the field. No one wants a penalty or an ejection to determine the outcome of the game. In recent weeks, however, there have been several suspensions and ejections because of contact with, and conduct toward, our game officials. This is not who we are -- as players, as clubs, as the NFL."

In a statement, NFLRA executive vice president Scott Green said: "We appreciate the league expressing its concerns to all clubs about abusive actions, both verbal and physical, toward officials. We would expect that any future actions will be met with appropriate and severe punishment."

Raiders running back Marshawn Lynch was suspended one game for making contact with an official this season. AP Photo/Ben Margot

NFL officials have ejected three players for making contact with them this season. One, Oakland Raiders running back Marshawn Lynch, was suspended for it. In Week 12, side judge Laird Hayes suffered bruised ribs while trying to break up a fight between the Denver Broncos and Raiders. And in Week 13, Cleveland Browns right tackle Shon Coleman was fined $30,387 for knocking over umpire Jeff Rice while chasing a loose ball.

Most recently, New Orleans Saints coach Sean Payton received an unsportsmanlike conduct penalty in Week 14 after charging onto the field at field judge Joe Larrew to call timeout. Payton later said that the game, which the Atlanta Falcons won 20-17, was officiated "extremely poor."

The memo said the league will "continue to emphasize enforcement of unsportsmanlike conduct rules with our officiating crews, and they will be encouraged to disqualify players for any offenses directed at them. Such offenses may also result in fines, and/or suspensions."

It is not yet clear whether Payton will be disciplined beyond the in-game penalty. Asked Monday about Payton's criticism, NFL spokesman Joe Lockhart said: "I think everyone is aware of the rules that are in place of public criticism of our officials, and those who need to be reminded occasionally are reminded."