Magic Johnson posted pictures on Twitter with the governor and mayor, as well as San Francisco Mayor London Breed, at SoFi Stadium during Sunday's NFC title game between the Rams and the San Francisco 49ers.
None of them are wearing masks for the photo, although Garcetti appears to be holding a mask in his hand.
California state Sen. Melissa Melendez criticized Newsom and Garcetti in a post to her Twitter page:
"Toddlers are being forced to wear masks all day long in school. Maybe one day they'll be governor or the mayor of L.A. and they won't have to follow the rules they impose on others."
Both Newsom and Garcetti said on Monday that they were wearing masks throughout the game, but only removed them to pose for the pictures.
"I was very judicious yesterday, very judicious," Newsom told reporters on Monday.
"You'll see the photo I did take. Magic was kind enough, generous enough to ask me for a photograph. In my left hand is a mask and I took the photo. The rest of the time I wore it, as we all should. Not when I had a glass of water. And I encourage everyone else to do so."
A Garcetti spokesman said: "He was wearing a mask at the game and removed it for a brief moment to take a few photos."