ROME (AP) _ Cuban leader Fidel Castro says President John F. Kennedy was ''a tough opponent,'' while President Reagan's characteristics are ''improvisation and incoherence.''

Castro was interviewed for a program to be broadcast Saturday on the state- run RAI network. The 2 1/2 -hour interview, screened in advance for journalists on Thursday, was taped in Cuba in June.

''Kennedy was a tough opponent, but at least he had a plan - an alliance for progress, an idea for not letting Latin America die,'' Castro said of his opponent from the 1962 Cuban missile crisis.

''Reagan doesn't even have one project - his characteristics are improvisation and incoherence,'' Castro said.

On the subject of human rights, Castro said: ''Everyone has always come out of our prisons in good health - I don't know if you Europeans or the Americans can say the same thing.''