The two rival Palestinian factions have failed to heal their political disputes since Hamas fighters expelled Fatah from Gaza in a short war in 2007
"Fidel Castro is dead!" he said in Twitter without elaborating on Saturday.
Trump, who takes office on Jan 20, threatened during his campaign to reverse President Barack Obama's moves to open relations with Cuba over concerns about religious freedom.
He was demonised by the US and its allies but admired by many leftists around the world, especially socialist revolutionaries in Latin America and Africa.
Transforming Cuba from a playground for rich Americans into a symbol of resistance to Washington, Castro outlasted nine US presidents in power.