The Canadian Vehicle Manufacturers' Association, which represents the Detroit Three in Canada, made a similar call to action.
"Tariffs on vehicles and parts will reduce North American vehicle production, increase vehicle prices, and lead to job losses at manufacturing facilities across the continent," the group's CEO Brian Kingston said in a statement.
The immediate impact on Canadian assembly plants is not yet known.
Stellantis would not comment on its plans, deferring comment to the CVMA. Ford, General Motors, Honda and Toyota could not immediately be reached for comment outside regular business hours.
Unifor, which represents hourly workers at Detroit Three plants in Canada, said Trump "has declared a trade war" with Canada.
"Trump's decision to go to battle with America's largest trading partner will hurt working people on both sides of the border and inflict real economic damage to both countries," union President Lana Payne said in a release.
Federal and provincial governments, meantime, quickly vowed to retaliate against the U.S. tariffs, despite White House threats of escalation should Canada do so.
Prime Minister Justin Trudeau said the tariffs violate the United States-Mexico-Canada Agreement finalized in 2019 and have potential to shut down auto plants in the U.S.
Canada's retaliation includes 25-percent tariffs on $30 billion in U.S. imports starting Feb. 4 and $125 billion in imports in three weeks' time.
Earlier on Feb. 1, Ontario Premier Doug Ford said he fully supported the federal plan to "hit back hard."
"There's no sugarcoating this. The coming weeks and months will be some of the toughest we've ever faced," he told reporters in Brampton, Ont.
"The impact of these tariffs will be felt almost immediately. Companies' orders are going to slow down. Factories will have to reduce shifts. Workers may lose their jobs."
The APMA's Volpe said Trump does not care about the thousands of jobs at risk in Ontario but will be forced to confront blowback at home.
"He's going to have a hard time listening to senators in his own party, influential Congressional reps, governors, union leaders, people, Americans, who will feel the full brunt of what he tried to do to us."
Greg Layson, Automotive News staff, contributed to this report.