A national outcry over police violence against minorities, particularly black people, has been sparked off by several high-profile police killings of unarmed black men in cities like Ferguson, Missouri and New York over the past year.

The video dates from January and was published on YouTube by the American Civil Liberties Union of Southern California.

The woman's arrest was wrongful, ACLU attorney Jessica Price told television news channel CNN.

"It's pretty horrifying," she added. "A lot of people are going to look at this and going to say there is some level of racial profiling and bias going on here."

The clip shows police officers in the city of Barstow speaking to a white woman who accused the pregnant woman, Charlena Michelle Cooks, of having attacked her car after the two got into an argument over driving.

"I don't see a crime that has been committed," says one of the officers, before walking to Cooks, who said she was dropping off her daughter at school at the time of the incident.

In the video, Cooks denies the accusation, saying she and her daughter were the ones who felt threatened by the woman. The video then shows the officer ask for her name and she refuses.

Soon after, the video shows the two male officers wrestle the woman to the ground, as she screams that she is pregnant and pleading with them to let her go.

"Please, I'm pregnant!" she screamed several times and repeatedly asked the officers not to touch her.