Police responded on Saturday morning after some Ottawa residents posted photos on social media that showed the graffiti.
One piece of graffiti promoted racism while a second piece promoted antisemitism.
Police are investigating and officers say it is a potential hate crime.
Ottawa Police Chief Charles Bordeleau tweeted police protocol is to gather evidence before the messages are removed. City crews were also dispatched to the graffiti, according to Steve Kanellakos, deputy city manager of operations.
It is National Capital Commission property but the City of Ottawa said it hoped to remove the messages quickly.
Ottawa police's hate crime unit also said it is investigating 20 cases of "concerning" graffiti found over the past month.