Can you do a masters in Canada with 3 years bachelor degree?
Most Canadian university will admit you to a master if you have an undergraduate degree. This could be a “license” in the European system or a bachelor degree. The reason why universities require a four year degree is because there is no College in the Canadian system ( with the exception of Quebec with its cégep system). Consequently, students enter universities at a young age ( around 17 or 18). If you have completed a bachelor equivalent I would try to apply. School registrar will judge your application based on which education system you are from.
Good luck in your application !