It's more likely the case that an American credit card holder cannot buy them, even when he is in Germany, because he's subject to American laws, as I would be if I took a box into the US and started selling them.
It went so far that PayPal, VISA and MasterCard ended up threatening several German store chains to stop selling products from Cuba or they’d end all business with the store
It went into national media, and was discussed on reddit: https://www.reddit.com/r/technology/comments/ka26b/paypal_bl...
Rossmann won against PayPal in court, to this date they don’t offer any payment via PayPal.
They came to an agreement with VISA and MasterCard, where if a sale contains embargoed products, everything but these products can be paid by card, but the embargoed products can not.
But that’s the point.
Cuban Cigars are legal in Germany.
You can legally buy them.
But every payment processor that’s located in the US can not process such a transaction.
Relying on foreign companies for most basic needs means you lose a lot of sovereignty.