9:12 AM PT -- Sources close to Danielle tell TMZ ... the feud was actually sparked after Danielle claimed Vicky used a racially derogatory term to describe one of her best friends at a birthday party.

Danielle Bregoli confronted fellow social media star Woah Vicky to settle their smack-talking beef ... and all hell broke loose.

The incident went down Sunday in L.A. where Danielle -- aka Bhad Bhabie -- went after Vicky ... an 18-year-old Instagram star who claims to be a billionaire. The feud apparently started after Vicky called out Danielle in a post.

Anyway, the fight video starts with Danielle and her bodyguard going up to Vicky, who was with 9-year-old rapper Lil Tay. Words are exchanged and Danielle threw a haymaker before leaving the scene.

Danielle later deleted a post on social media that said, "Don't be showin up tryin to film me to get views. I shouldn't have cracked dhat hoe like I did, but whatever. She a joke. Moving on."

Vicky and Tay tell a different story.