The protesters, part of the group "Indivisible San Pedro," spelled out the word "RESIST!" in 30-foot-tall letters in a public park on the grounds of the golf club, located in Rancho Palos Verdes, reported ABC affiliate KABC.
The group has also been vocal about urging the president to release his tax returns.
It took the flash mob -- which consisted of children -- about 15 minutes to form the word, after which they sang "God Bless America," according to The Los Angeles Times.
Los Angeles County Sheriff’s deputies were reportedly called to the scene and watched from clubhouse balcony, but they did not intervene or arrest anyone.