"Sadly, the protesters’ message gets erased when you have certain organizers inciting violence, which is what a handful of them are doing," the Pittsburgh police chief said.

PITTSBURGH (KDKA) — Pittsburgh Public Safety is calling the viral video showing a clash between protesters and restaurant patrons “unacceptable.” They say if any laws were broken, charges will be filed.

Footage from a demonstration in downtown Pittsburgh over the weekend has been blowing up on social media. The viral video showed demonstrators and restaurant-goers clashing in the streets.

“People have the right to dine in public without being accosted and without vulgarities being thrown at them,” Public Safety Director Wendell Hissrich said in a statement Tuesday. “What we saw this weekend was assault and battery. It was embarrassing. The vast majority of the protests in Pittsburgh have been peaceful, but this weekend was anything but peaceful.”

Pittsburgh Police are working with the U.S. Attorney’s Office and FBI Pittsburgh to investigate, which includes collecting video evidence and trying to interview witnesses.

(Photo Credit: Facebook)

“As a native Pittsburgher, what I saw this weekend was disturbing and cannot continue. Sadly, the protesters’ message gets erased when you have certain organizers inciting violence, which is what a handful of them are doing,” Police Chief Scott Schubert said in a statement.

“It creates a dangerous and volatile situation. Our goal, now and always, is to maintain safety for everyone, and that includes protesters, residents, visitors, business owners and patrons and our police officers who are working under difficult conditions to serve the public.”

The clash between protesters and restaurant-goers is garnering national attention, with even President Donald Trump tweeting a reaction Tuesday morning calling the protesters “anarchists.”

The woman who posted the viral Facebook video online said she was “shocked” when the crowd rolled past her dinner table. The video showed protesters screaming insults at restaurant-goers as some left their tables.

A person can be seen walking over to an elderly couple, grabbing a beer off their table and drinking it.

“Who thinks it’s ok to go up to somebody who is at a restaurant and take food off their plate and beverage off their table?” U.S. Senator Pat Toomey told KDKA.

He said it’s not acceptable and they should be prosecuted.

Another video showed demonstrators chasing away a group of people who rode their bikes through the crowd. One of the riders is seen in the video smacking a bullhorn that belonged to one of the protesters, then getting whacked over the helmet with a skateboard.

Jerry Dickinson, Activist, and Associate Professor of Law at the University of Pittsburgh told KDKA, “When you have incidents where you are engaging in harassment or disorderly conduct, that’s not going to be protected by the first amendment.”

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“Recent studies show 90 percent of protests across the country have been peaceful,” said Dickinson.

Following a weekend demonstration outside his house, Mayor Bill Peduto tweeted “Tonight at my home – private property. The 1st Amendment doesn’t protect you to close down streets, without a permit. Yes, we have granted extra rights to assure free speech. But, continual denial of law, will end up in arrests. Actions have consequences.”

Dickinson said the mayor should be more clear on the rules.

“It’s extremely important for our elected officials to be communicated clearly and concisely” he said.

The restaurant, Sienna Mercato, says, “Although we support the right to a peaceful protest, violence and destruction are not the answer.”

KDKA reached out to Pittsburgh Mayor Bill Peduto and was told he wasn’t available today.