Kinsler, who has been in a season-long slump, broke out of it with a blast to right field in the sixth inning off Pirates reliever Richard Rodriguez.
Per the Associated Press, some fans on social media believed Kinsler appeared to say "f--k" in a way that was directed toward people who were criticizing him for his struggles this season.
"That was for my teammates," Kinsler told reporters. "It had nothing to do with the fans. It's for my teammates. It's an inside thing with them. Just trying to get everybody fired up. We had a tough road trip. I'm a passionate player. I try to get my teammates going. That was it."
During the postgame press conference, Padres manager Andy Green defended Kinsler's emotional response in the heat of the moment.
"The world we live in, you hear a lot of hostility and some of that comes out [at] times," Green said, per USA Today's Tom Schad. "It’s not the right response, but understanding the emotion of the game, that’s probably the best response."
Even after his three-run homer Thursday, Kinsler has been one of the worst position players in Major League Baseball this season.
The 36-year-old is hitting .175/.233/.342 with five homers in 37 games, and his -0.7 FanGraphs wins above replacement is tied for the fourth-worst total among 203 players with at least 120 plate appearances.
But San Diego hasn't been hurt by Kinsler's lack of production with a 23-21 record. The Padres finished last season 30 games under .500.