Norris was penalised for slowing down too much under the safety car on lap 12, thereby leaving a gap with team-mate Oscar Piastri, which gave McLaren more breathing space to perform a double pitstop.
The FIA stewards gave the Briton a five-second penalty for "unsportsmanlike conduct" in their verdict: "The driver slowed under the Safety Car to avoid a delay during a 'double stack' for his pitstop.
"During the Safety Car period the driver slowed to allow a gap to form between his team-mate in Car 81 and him. In doing so he delayed the cars behind.
"There was a significant difference in speed between Car 4 and Car 81 between Turns 10 and 13 (approximately 50 km/h).
"Article 12.2.1.l of the ISC refers to 'any infringement of the principles of fairness in competition, behaviour in an unsportsmanlike manner or attempt to influence the results of a competition, in a way that is contrary to sporting ethics'."
When asked about his transgression by Autosport, Norris said no idea why he was penalised.
"The team didn't tell me, so I have no idea what I got a penalty for," he replied.
Once he was brought up to date, he said: "I only got told to box like three seconds before the box. By that time I was flat out, so it doesn't make sense to me.
"There are plenty of times where you go slow under VSC. So, if I get a penalty today I should get a penalty for the last three years as well and so should everyone else.
"But no, I don't think I did anything wrong."
Lando Norris, McLaren MCL60, Charles Leclerc, Ferrari SF-23, Alex Albon, Williams FW45
Photo by: Jake Grant / Motorsport Images
The time penalty was added to his race time at the finish and dropped Norris from ninth to 13th, voiding his efforts to score points after a tense midfield scrap with Alpine's Esteban Ocon and Alfa Romeo's Valtteri Bottas.
Despite the result Norris said Canada was his best race so far in 2023: "It was my best races of the year I would say. One of my first overtakes of the year today, it was a good race.
"I lost a position [to Piastri] but I made it back. All my overtakes were in the hairpin, I was really confident on the brakes.
"The pace was good, I wouldn't say it was amazing, but good enough to hold on to the Alfa and the Alpine and have a chance to at least race them."