One anti-vaccine activist at the rally urged others to "make them afraid" at an upcoming event involving children and parents walking to school.
Wednesday is national Walk to School Day.
"They think it's gonna be a fun and safe photo opportunity with parents and kids," said one speaker at the protest. "Let's show up here and show them it's not. Let's show them how we really feel."
"Let's make them afraid."
The Beverly Hills Courier identified the speaker as David Hakimfar, a West Hollywood attorney and anti-vaccine activist.
The city of Beverly Hills is requiring firefighters among other employees to get vaccinated.
The city notes it wasn't their decision, but a mandate from Los Angeles County. The county is requiring vaccinations for all health care workers, including paramedics and emergency medical technicians, by Oct. 1.
The firefighters union is fighting the mandate.
The Beverly Hills Firefighters Association posted recently on Facebook that while it recommends and encourages members to get vaccinated, the union believes it should be left to personal choice.
"What we aren't in agreement with is the mandate by Los Angeles County Department of Public Health and strongly believe it should be a personal choice on whether one receives the vaccination or not," the union said.
"Our Association is made up of many members of different backgrounds and beliefs and we will always stand with one another to allow each and every member to make decisions that are best for them and their family."
As of Friday, the city said, 25 of the department's 97 firefighters have requested exemptions from vaccination for religious or medical reasons. Six of them have been denied exemptions - and of those, five have since been vaccinated and one was placed on unpaid leave. One firefighter was granted a medical exemption and 18 others have been granted temporary medical or religious exemptions for 30 days as their requests are reviewed.
"I want to assure the Beverly Hills community that this department will continue to provide world-class care with full staffing and emergency medical technicians on all shifts," said Fire Chief Greg Barton.
"The County's requirement for vaccination of first responders is now in effect. While personal opinions on the issue of requiring vaccination vary, it is the City's duty and responsibility to follow the County's directive. I will not allow anything to distract from our mission of protecting the health and safety of the community."