The NFL has filed a grievance with the players' union asking Saints linebacker Jonathan Vilma to drop his defamation lawsuit against Commissioner Roger Goodell.

The league claims Vilma's suit violates the collective bargaining agreement reached last August to end the lockout. A clause in the CBA, which the NFL says the union agreed to, bars NFL Players Association members from suing the league or any clubs.

Vilma tweeted in response to the NFL's grievance: "The nfl sent me a letter "demanding" I drop my defamation suit or else...lol or else wat?!?? They no likey me lawsuitey."

Vilma has been suspended for the 2012 season by Goodell for his role in the Saints' bounties program that the NFL says was conducted for three years. Vilma also is seeking an injunction to stop that suspension from taking effect.

The New Orleans Times-Picayune first reported the NFL's grievance filing.

In its grievance, the NFL says "imposition of discipline against Vilma" is covered by Article 46 of the CBA. "Clearly, league discipline, and the commissioner's responsibility for upholding that policy, is conduct permitted by the CBA and under the NFL's constitution and bylaws."

Vilma's defamation suit accuses Goodell of making "very public and unfortunately erroneous allegations against Jonathan," said Vilma's attorney, Peter Ginsberg. "By making these false and public statements, he has significantly harmed Jonathan's reputation and ability to make a living.

"By suing Commissioner Goodell in court, Jonathan opted to use a fair playing field where he has procedural rights and protections to remedy the harm Commissioner Goodell has done to him."

In response to the grievance, Ginsberg said the CBA clause is not valid because Vilma is not suing a club or the league itself, but only Goodell.

"The CBA has a no-suit clause and we needed to file a grievance in order to be able to assert our rights under that clause," NFL spokesman Greg Aiello said Thursday. "We disagree with Mr. Ginsberg's characterization of the grievance. We are following the CBA process; he is not."