Clashes broke out July 18 when Israeli supporters arrived at a demonstration in support of Palestinians killed by Israeli fire in Gaza.
Some men began pushing and shoving, and one man stomped on an Israeli flag before police moved in and separated the groups.
Police say an investigation has led to assault charges against two men and one teenage boy — all from Calgary.
They say charges against a fourth man are expected soon.
The three accused are to next appear in court Sept. 15.
Charged with assault are Aziz Mohammed Madi, 18; Arlsan Khan, 27; and a 16-year-old youth, who cannot be named under provisions of the Youth Criminal Justice Act.
Investigators also are asking for the public's help to identify a man who may be able to provide useful information about what happened.
Insp. Cliff O'Brien says the search for the man may not lead to charges, but it's important police speak to the individual.
"What we're asking for is for people — if they know who this person is or if the person sees themselves — to phone us, so that we can have a conversation with them and find out exactly what role, if any, they played in this," O'Brien said Tuesday.
The man is described as having an olive skin tone, dark hair, a slim build and as speaking with an accent. Police say he was wearing jeans, a white T-shirt with a Dulux logo on it, white runners and a tan baseball cap. His clothing and hands were stained with white paint.
O'Brien said the investigation is far from over.
"We're continuing to look for other videos, other still photographs, other witness or victims who may come forward," he said. "As of (Monday) night there was still new information that was coming in and the investigators and the investigative team will look at that information."
— With files from CHQR