Diane Johnston, one of the protesters, says Canada and the United States need to stop meddling in other the affairs of other countries.
The rally began near a downtown cenotaph, where a vigil was held a day earlier for the two Canadian soldiers killed in the past week in two separate attacks in Ottawa and near Montreal.
Johnston says those events were tragic but it doesn't change her belief that Canada shouldn't engage in military action, which creates more problems than it solves.
More than a hundred people were on hand for the protest.
Six Canadian fighter jets left on Tuesday to join the mission in Iraq.
The CF-18 Hornets headed to Kuwait, which will serve as Canada's base of operations. About 600 personnel, along with the jets, two surveillance planes and an aerial tanker, will be based there.