Pettigrew was called for a personal foul in the fourth quarter of Detroit's 31-17 loss. He made contact with an official who was trying to get between him and Saints safety Roman Harper after the whistle.
"I want to sincerely apologize to my teammates, my coaches, the Lions organization, fans and the NFL for my actions during the game on Sunday. In the heat of competition, I allowed my emotions to get the best of me," Pettigrew said in a statement Tuesday. "I know better and my unintentional mistake cost my team. I've never acted this way before and it won't happen again. I am fully committed to helping the Detroit Lions win with class and in a manner that our fans will respect."
Detroit has lost five of seven since a 5-0 start and drawn criticism for the on-field behavior of its players. Defensive lineman Ndamukong Suh is serving a two-game suspension for roughing up a Green Bay lineman in a Thanksgiving loss to the Packers.
Pettigrew has 56 catches for 475 yards this season.
Coach Jim Schwartz discussed Pettigrew's penalty Monday and didn't sound concerned about possible additional discipline.
"The official on the sideline said, 'Hey look, I stepped in between two players and he didn't know that was me,' " Schwartz said.
With the Lions drawing so much attention from the league office, commissioner Roger Goodell is planning to attend this weekend's Vikings-Lions game in Detroit and will hold a fan forum before the game.
The league confirmed Goodell's plans Tuesday night and said more details would be announced Wednesday. Detroit takes on Minnesota at 1 p.m. Sunday.
Information from The Associated Press contributed to this report.