In a message on Saturday, Zarif described Castro as an exceptional figure in the fight against colonialism and exploitation and a “role model” for the oppressed nations struggling for independence.
The Iranian top diplomat further paid tribute to the late revolutionary leader and prayed that his soul rest in peace.
Fidel Castro, who built a communist state on the doorstep of the United States and defied US efforts to topple him for five decades, died on Friday at the age of 90.
Fidel Castro took power in a 1959 revolution and ruled Cuba for 49 years with a mix of charisma and iron will, creating a one-party state and becoming a central figure in the Cold War.
He was demonized by the United States 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.
He fended off a CIA-backed invasion at the Bay of Pigs in 1961 as well as countless assassination attempts.
His alliance with Moscow helped trigger the Cuban Missile Crisis in 1962, a 13-day showdown with the United States that brought the world the closest it has been to nuclear war.