State law has allowed licensed peace officers to carry weapons in private areas since 2003.
But in September, the NFL told team owners it was implementing a new policy that would only allow on-duty officers and private security personnel to carry weapons in a stadium.
The lawsuit, which was filed Tuesday, says the policy violates state law and is unenforceable, the Minneapolis Star Tribune reported.
Dennis Flaherty, the executive director of the Minnesota Police and Peace Officers Association, cited an incident at a Minnesota Vikings game when an off-duty officer was told to take his gun and lock it in his car.
"This is the most unsafe thing you could do," he said. "Officers are trained and encouraged to be able to respond 24 hours a day. This is terrible public policy."
Lt. John Delmonico, the president of the Police Officers Federation of Minneapolis, said the suit appears to be the first one challenging the NFL policy.
The NFL has defended its policy and said that public safety is best served by on-duty officers who are assigned to the game.
Many off-duty officers haven't received special training on working in a stadium and are not familiar with the on-duty officers, the NFL said.