You can't bring any into the US. They will be confiscated. The law can actually be interpreted to mean that as an American citizen, you are not allowed to purchase Cuban products ANYWHERE in the world. Of course, this is a bit difficult to enforce.

If they're for personal use, you can try to get around it by being sneaky. Here's an idea. Take an empty used cigar box of a generic brand with you or get one in Canada. Maybe have a couple domestic stogies for looks. Take off the cigar labels and fill with bare unlabeled Cubans. Pack haphazardly in your luggage. Take some out to make it loook like you opened the box and smoked a couple. If you want the cuban labels and cigar box, mail the labels flattened in a letter to yourself. Send the cigar box to yourself wrapped in brown paper and packed with personal effects, candy, baked goods, or something else innocuous.

Mind you I've never done this, but a small quantity like this shouldn't gain too much attention. Without the labels and box , how to prove they're Cubans?