Simcoe Hall was struck by vandalism overnight, with the word “SHAME” painted in red on the front of the building.
The building houses a number of administrative offices, including the office of the president and the Governing Council Chamber.
“[Toronto Police Services] is investigating the graffiti incident on Simcoe Hall, which is a listed heritage building,” said Michael Kurts, University of Toronto assistant vice-president, strategic communications & marketing.
Kurts declined to say who may be behind the incident, adding that the university has no other information to provide at this time.
Restoration crews were on site on Friday morning, with the graffiti removed from the building by midday.
Also on Friday, Toronto Police Services cleared Simcoe Hall after the building was evacuated following reports of the smell of smoke.
“While it is not known who may have committed this act or if they are connected to any group or the strike, CUPE 3902 condemns the act,” said CUPE 3902 chair Erin Black in a statement.
“To vandalize a building in the heart of the St. George campus does not advance any one’s cause. Rather, it only serves to distract attention from where it needs to be, resolving a labour dispute that is hurting the university community,” the statement adds.