Mr Castro, in a column published in state media, said it was too early to evaluate what was happening in Libya.
But, he said, it was clear the US would not hesitate to order Nato to invade.
Mr Castro led Cuba for almost 50 years after the 1959 communist revolution before officially handing over to his brother Raul in 2008.
In his latest "Reflections", Fidel Castro outlines the importance of oil and what he argues is the long-standing aim of the US to control supplies.
"What is for me absolutely evident is that the government of the United States is not worried at all about peace in Libya," he writes. Read More