I'm from Sweden, not USA. I think there are many problems with USA, but it isn't capitalism at least, I'd say the major problem is that their democracy doesn't properly represent the will of the people. Sweden isn't perfect, but I don't see many countries that does a better job, and Sweden is very capitalist, we voted about going towards communist but people didn't want to. Instead we have a strong capitalism, but with relatively high taxes and high government benefits, but other than that governments doesn't meddle much with companies, so freedom to do business is very high.
If Cuba was a democracy then I would disagree with the sanctions, but I don't think it is wrong to pressure a government into giving proper voting rights to its people. If Cuba actually implemented democracy and USA still sanctioned them then that would be bad, but that isn't the situation we are in.