A white woman in San Francisco who called police on her neighbour for writing Black Lives Matter in chalk on his own property has apologised.

“I did not realise at the time that my actions were racist and have learned a painful lesson,” Lisa Alexander said in a statement to US news station ABC.

Alexander, CEO of the La Face skin care line, reportedly is already suffering professional consequences since video showing her and her partner confronting James Juanillo in the posh Pacific Heights neighbourhood went viral. Her partner was fired from his job at financial services firm Raymond James, the company said.

Juanillo, who identifies as Filipino, took the video of his neighbours confronting him as he stenciled Black Lives Matter on his retaining wall. They later called the police, who recognised Juanillo and didn’t get out of their squad car, he said.

Birchbox announced it had severed ties with Alexander’s brand, SFGate reported, and the La Face website appeared to be inaccessible as of Monday morning.

In the video, posted Thursday, Alexander warned Juanillo that he was illegally stenciling and said she knew the property owner. Juanillo, who has lived in the building for years, welcomed her to call the police ― and she did.

As Juanillo’s video shows the couple leaving, the camera cuts to his stenciling in block letters and he says, “And that, people, is why Black lives matter.” 

“I should have minded my own business,’’ Alexander wrote, proposing a coffee date with Juanillo so she could apologise in person.

Last month in New York City, a white woman named Amy Cooper caused a stir by calling the police on a Black man who asked her to put her dog on a leash in Central Park. She responded by saying she’d call the police to report “an African American man” was “threatening” her life. Her financial services employer fired her.