Barnes was ejected from the game after he made contact with an official. A league spokesman said Friday that the specific reason for the fine was unnecessary physical contact with an official.
Barnes had a breakout season for the Chargers in 2011, finishing with 11 sacks.
Walden was penalized by the league on Friday for striking Detroit Lions quarterback Matthew Stafford in the head and neck area. He was whistled for a penalty in the third quarter of Green Bay's 45-41 victory last weekend.
Bill Williamson is ESPN.com's AFC West blogger. Information from The Associated Press was used in this report.