Pro-Palestinian rally organizers are apologizing for the violence seen last Friday at Calgary's City Hall.

Hundreds attended the protest to call for a ceasefire and condemn the current attacks in Gaza but it turned ugly when Israel supporters came to stage a protest of their own.

"We completely denounce that and want to make sure our message goes out to the people who were hurt in that that we apologize," said Saima Jamal with Justice for Palestinians.

Organizers of a pro-Palestinian rally at Calgary's City Hall are denouncing the violence seen last week. (CBC)

The Calgary Jewish Federation (CJF) say the violent outbursts were assaults, and today condemned the violence.

"It was a very scary and disgusting scene," said CJF member Judy Shapiro, who was at the rally as an observer. "Nobody on the streets of Calgary should be beat up for their opinions."

While she was not involved in the altercation, she says one young man has a concussion, a young woman was punched in the face and another young man has a broken nose.

She said they were there because they feel strongly about supporting Israel — even though emotions are running high from the latest conflict in Gaza.

Shapiro says it is also about freedom of speech.

"It goes two ways. Everybody has that right," she said.

Mayor Naheed Nenshi said in a statement that "what makes this country work is the fact we can live together and disagree on things respectfully."

While Calgary police have not laid any charges, Nenshi says they will investigate any allegation of physical violence and press appropriate charges if supported by evidence.

'Communication drop' around policing rally

Rally organizers say it was only a very small handful of protesters who let their anger get the best of them after days of seeing horrible images come out of Gaza, such as four young boys killed on a beach.

Jamal hopes the clash with Israeli protesters won't take away from the rally's message. She would like to see the Canadian government do more to stop the deaths of Palestinian people.

"I want to focus on the thousands of Calgarians that we have mobilized to come from every background possible that are coming together to call in one voice to stop the bombing of Gaza and Israel," she said.

Jamal says they did contact Calgary police before the rally. Police eventually showed up, but only after the fights.

Police spokeperson Kevin Brookwell says they should have been there.

"We were in communication with both groups," he said. "We anticipated we were going to have police presence there right at the start.... There was a communication drop and we didn't have anybody at the site, but officers close by."

Both Palestinian and Israeli supporters have already contacted police ahead of another rally planned this Friday from 6 to 8 p.m. MT.

Police say this time they will be there in full force from the beginning. There will also be 50 volunteer marshals on hand to keep the peace.

Organizers hope that presence won't be needed and they encourage Israel supporters to attend.

"We want you to come again and hold hands with us," she said.

"If we cannot as Calgarians come together peacefully, how are we going to bring peace over there?"