Dumontet, 45, allegedly threw a bag containing a glass bottle, striking a child nearby.
LAPD records confirm Dumontet's arrest on Tuesday, with bail set at $30,000.
Christine Quinn and Dumontet married in 2019, featured in "Selling Sunset" Season 3.
The couple shares a 2-year-old son, Christian Georges Dumontet.
Quinn left "Selling Sunset" in 2022 to start her own brokerage, RealOpen, citing a toxic environment at her former workplace.
Quinn claims her departure wasn't a surprise to producers, who knew for a year and a half about her plans to start her own company.
Producers allegedly fabricated a bribery scandal involving Quinn for dramatic effect on the show.