Lots of Canada flies directly to Cuba (Halifax, Montreal, Toronto[0]). There are (or were?) some historical "can't use US airspace" rules about flights travelling there (so western Canada has to connect).

[0]: https://www.aircanada.com/en-ca/flights-from-canada-to-cuba

There’s only one direct flight and that’s from Miami with American Airlines.

You have a lot of research to do if you think the problem is the embargo.