It always amazes me that in this internet age so many people rely on message boards to ask questions that may have very serious consequences if you get it wrong.
Here is a quote I got from the a google search about the legality of US citizens traveling to Cuba.
The U.S. enacted a hard-line trade embargo that restricted travel, and to this day U.S. citizens looking to visit Cuba have to acquire permission from the U.S. Department of the Treasury’s Office of Foreign Assets (OFAC). OFAC “prohibits persons subject to the jurisdiction of the United States from engaging in transactions in which Cuba or a Cuban national has any interest whatsoever, direct or indirect, including transactions related to travel,” reads the official documentation on Cuba sanctions, available here.
Ask this question to OFAC.