The NFL fined Peters $13,369 for grabbing his crotch as he jumped backward into the end zone for a touchdown during a season-opening victory in Oakland on Monday night.
"Yeah, it's a lot of money," Peters said after practice Friday. "But it was worth it."
Rams coach Sean McVay said he thought the celebration, dubbed "The Beast Mode" by Peters, was good-natured.
"He's got a close relationship with Marshawn," McVay said. "This was something that he had discussed with him before, if he was going to be able to make a play like that. So it was a good way for those guys to kind of have an inside joke, laugh about it, and I think it all was in fun and lighthearted."
Peters, who grew up in Oakland, intercepted a pass by Derek Carr with 1:59 remaining in the game and returned it 50 yards for the score.
Peters, acquired by the Rams in an offseason trade with the Kansas City Chiefs, finished with three tackles, an interception and a pass deflection in the 33-13 victory. Afterward, McVay awarded Peters with a game ball.
"It's all paying respect and loving the game," Peters said of his touchdown celebration. "... Who knows if this [is] Marshawn's last year playing in the league. S---, we was up, closed the game out, no better way to go out in Oakland. Who knows the next time we'll get to play the Raiders in Oakland. They're going to Vegas in what, a year and a half?
"So it was something that was well-deserved for the hometown."
Lynch, also from Oakland and whom Peters refers to as his cousin, incurred a similar fine, $11,000, in 2014 for the same gesture. Lynch was fined $20,000 for doing it again a month later.
Peters' fine was not even the largest that a Rams player incurred after last week's game. Defensive tackle Aaron Donald was fined $20,054 for roughing Carr.
"It was a low hit. Not much you can do when you're falling," Donald said. "But it is what it is."