Images of a seemingly defenseless woman bowled over by police in riot gear in St. Louis swept the Internet on Saturday as protests roiled that city for a second day.

Demonstrators marched through two malls Saturday chanting, “Black lives matter!” after a white police officer was acquitted in the 2011 fatal shooting of a black man.

There were no arrests.

But Friday, raucous marches in downtown culminated in smashed windows, rocks and paint being thrown at cops and at the home of Mayor Lyda Krewson.

Thirty-two people were arrested and 10 cops were hurt in the fracas, police said.

Amid Friday’s tense marches, the elderly woman, wearing a red top and white pants, appeared to try to stand her ground and yell at a group of officers when she was knocked over by the cops armed with pepper spray in an incident captured by a Fox TV affiliate’s news helicopter.

The woman “failed to obey officers’ orders,” and was charged with “interfering,” St. Louis police said on Twitter Saturday.

Charlie Brennan, a St. Louis radio host, backed the police account.

He wrote on Twitter: “She was telling others to stand behind her ‘because the police won’t bother an old lady.’ ”

The protests followed the acquittal by a judge of Jason Stockley in the death of Anthony Lamar Smith, 24, after the suspected drug dealer crashed his car following a chase.

Stockley testified he saw Smith holding a silver revolver as he sped away.

The officer, who has since left the St. Louis police and moved to Houston, said he felt he was in imminent danger as he was approaching the vehicle.

Prosecutors charged Stockley planted a gun in Smith’s car after the shooting. The officer’s DNA was on the weapon, but Smith’s wasn’t.

Dashcam video from Stockley’s cruiser captured him saying he was “going to kill this [expletive], don’t you know it.”

Less than a minute later, he shot Smith five times.

Judge Timothy Wilson said prosecutors didn’t prove beyond a reasonable doubt that Stockley murdered Smith or that he didn’t act in self-defense.

The former cop told the St. Louis Post-Dispatch, “It feels like a burden has been lifted, but the burden of having to kill someone never really lifts.

“The taking of someone’s life is the most significant thing one can do, and it’s not done lightly . . .

“I understand what the family is going through, and I know everyone wants someone to blame.

“But I’m just not the guy.”