American companies and the American Mafia at one point maintained strong influence over the Cuban government. Many Cubans resented this foreign control over their country.
From the early post-colonial days, the United States had invested heavily in Cuba. The disastrous economic situation brought on by wartime destruction made land and labor cheap for American companies.
This reached a climax during the rule of Fulgencio Batista. He had left Cuba for Florida after losing an election, but Mafiosi in the US convinced him to return.
Soon, the Mafiosi controlled and built hotels, casinos, and other tourist services. Headed by Meyer Lansky, they made huge sums of money, and always handed Batista a cut. In 1958, the Hotel Riviera went up. All of this attracted more tourism, while Cubans were forced into prostitution and poverty.
American business also increased its hold on Cuba. Cuban exports to the US decreased as US exports to Cuba increased. The US owned a quarter of bank deposits in Cuba, 90% of the electric and telephone services, and half the public railways.
The United States was so powerful in Cuba right before the Revolution that many Cubans blamed it for not putting an end to Batista's abusive rule. America's profit at the expense of the Cuban people did not go unnoticed, and hatred towards Batista and the current situation united Cubans with Fidel Castro.