The 24-year-old actress backtracked in a Snapchat post Monday after commenting on the 22-year-old singer's relationship with Richie over the weekend.
"What I said was selfish and pointless," she told fans.
Gomez had sparked the hashtag "#SelenaEndedJustinParty" by telling Bieber to stop posting photos of Richie on Instagram. The "Purpose" singer had complained about fan "hate" toward the model after posting pictures of himself with Richie online.
"If you can't handle the hate then stop posting pictures of your girlfriend lol - it should be special between you two only. Don't be mad at your fans. They love you," Gomez had said.
Gomez's comment set off Bieber, who snapped back, "It's funny to see people that used me for attention and still try to point the finger this way." The exes reportedly accused each other of cheating in later posts.
"Justin thinks Selena is all about attention," a source told Us Weekly. "She was always about making their relationship public and getting publicity, and he thinks that's what she is doing now."