With the new political regime in the U.S. expressing different feelings towards Cuba than the old regime who had been taking steps to normalize relations, Americans wishing to travel to Cuba have an understandable degree of uncertainty. U.S. based airlines have established routes, and are offering full refunds if governmental regulations change. There are cruises scheduled from the U.S. which also are subject to those regulations. I had the pleasure of taking a Celestyal Cruise around Cuba, Celestyal being based in Greece. U.S. citizens are allowed on this ship with their ability to provide the OFAC licensing and required health insurance. They leave from Montego Bay which was what I did, but also from Havana.
Even though there is an overnight port stay in Havana, everyone I spoke with on board wished they would have had more time in Havana, such an intriguing city! I have been looking into the latest on this, and find that booking the cruise and flights is easy peasey and straightforward, but not so much for the hotels in the fashion we are used to.
For Americans to secure hotel reservations in Cuba; it is still not as straightforward as one would hope by now, still mired down in the red tape of governmental bureaucracy. We have been anxiously awaiting U.S. based travel providers who work with international hotels on a grand scale to become established in Cuba. This process is happening very slowly, with minimal movement towards stronger relationships between U.S. based hotel booking providers and Cuban hotels.
~Working directly with Cuban hotels is still not possible due to legal restrictions, however U.S. citizens can book a Cuban hotel directly that is a part of an international chain that is not based in the U.S. or Cuba.~
There are only two within the old town area of Havana; the Iberostar and the Mercure. Iberostar is based in Spain, however they are not offering this property to U.S. residents through their website. The Mercure hotel is part of the Accor chain based in France, and they do have online booking for Americans through their website; with no cancellation penalty (pay at the hotel) and breakfast included.
~The other option currently is to reserve your Cuban hotel through a non-US based third party travel consortium. ~
You should be able to use your U.S. based credit card to gaurantee the reservation, but may need to pay cash at the hotel upon checkout.