While there is no evidence he ever had definite plans, he did at occasions seem to indicate as much. At the most we can imagine he toyed with the idea. The Cuban Missile crisis did show his desire to wield more power and having the USSR backing him up was quite the Viagara to his ego, to put it bluntly.
In at least one occasion he did seem to at least want to scare his neighbours into submission. If a full-scale invasion had followed, we will never know.
In 1977, at the height of the Cold War, Fidel Castro got himself into an argument with his neighbour, the Dominican Republic, over a confiscated fishing vessel. Feeling his ego wounded at espionage accusations he ordered a full-scale attack on the country's capital Santo Domingo. The attack was to take place in various stages.
The first was for a wing of MiG fighters to buzz the city. The second was to bombard the military installations.
Fortunately he never initiated the second stage. During the first the low-flying fighters had scared everyone so much, they promptly returned the vessel and dropped all espionage accusations. However, it was reported that the fighters had been sitting on the runway armed and ready. A full war was averted in the last minute.
The pilot that flew in Operation Pico
Would he? Could he?
This incident and others of his involvements throughout the world showed Castro's willingness to at least flex his muscles in his mission to spread Communism throughout the world. However, the loss of his only true ally the USSR as well as an economic stagnation did put a limit on his abilities and hamper any possible plans, if any.