The Victory Peace memorial in Coronation Park was defaced with the words "Canada will burn praise Allah" written in what appeared to be black marker.
City workers were called in to clean the bronze memorial, built in the 1990s.
Someone walking through the park on Sunday noticed the vandalism and reported it to authorities.
Police say they don't have any suspects at the moment.
The Canadian Council on American-Islamic Relations says it condemns the vandalism, calling it "senseless" and "ignorant."
"We call on witnesses to step forward to assist police in finding the perpetrators of this sacrilege," Ihsaan Gardee, executive director of the council, said in a statement Monday.
"An act against a Canadian memorial site is an act against our shared history and an act against a sacred space," Gardee added.
(CFRB, The Canadian Press)