Lynch celebrated the score, a career-long 79-yard run, with a backward dive and obscene gesture. He wasn't flagged on the play.
Cardinals defensive tackle Frostee Rucker called Lynch's move "childish" after the game but didn't take offense to the gesture.
Lynch has 12 touchdowns and 1,246 yards on the season.
In other fines:
New York Giants wide receiver Preston Parker and defensive end Damontre Moore were fined $15,000 each by the NFL for their roles in a brawl during last week's game against the St. Louis Rams. Other fines levied as a result of the brawl: Rams DE William Hayes and Giants WR Odell Beckham Jr. were each fined $10,000, and Rams LB Alec Ogletree, whose hit on Beckham Jr. that continued out of bounds and ignited the melee, was docked $8,268.
Also, Giants defensive tackle Cullen Jenkins was given a $16,537 fine for roughing the passer. Kicker Josh Brown was docked $8,268 for unnecessary roughness, and snapper Zak DeOssie was fined $8,268 for a late hit.
Detroit Lions defensive end Ezekiel Ansah was fined $22,050 for unnecessary roughness while hitting Chicago quarterback Jimmy Clausen. The hit gave Clausen a concussion that will keep him from playing in Sunday's finale for the Bears.
Also, Bears tight end Martellus Bennett was fined $22,050 for abusive and insulting language toward an official in last Sunday's Lions-Bears game.
Oakland Raiders defensive lineman Justin Tuck was fined $22,050 for unsportsmanlike conduct (directed abusive and insulting language towards a game official) in his team's 26-24 win over Buffalo on Sunday.
Tuck was unhappy after a high-low hit by Buffalo lineman was called. The penalty was out of character for Tuck, generally known as a respectful player and a team leader.
ESPN.com's Josh Weinfuss, Michael Rothstein and Bill Williamson contributed to this report.