Wednesday's meeting was the first time in several months that the 87-year-old former President of Cuba met a foreign dignitary.
The last meeting Castro had with any visiting dignitary was perhaps with Venezuelan President Nicolas Maduro in July. Castro has been in poor health and demitted office in July 2006.
While Ansari was visibly pleased with the talks he had with Castro, further details were not available immediately. India's Ambassador to Cuba C Rajshekhar and Cuban Foreign Minister Bruno Rodriguez Parrila were also present at the meeting held at Castro's residence.
Till afternoon, Indian officials were saying that the meeting with Castro was "not confirmed". After concluding a "landmark" tour of Peru during which four agreements were signed, Ansari arrived in Cuba on Wednesday.
Ansari had earlier signed four agreements in Peru
Despite the two countries working closely in the NAM, it is the first ever bilateral visit by any Indian VVIP to the Communist country, as earlier trips by Prime Minister Manmohan Singh and others were in connection with multi-lateral events and meetings.
Cuba and India have a strong relation since the Communist revolution in the Carribean nation in 1959. India was among the first countries to recognise Communist Cuba led by Castro and then Prime Minister Jawaharlal Nehru was among the first major world leaders to visit Havana in 1960.
The personal role of Castro in forging the India-Cuba alliance is well known. The image of him embracing Indira Gandhi while handing over the NAM chairmanship to her in 1983 has become iconic. Castro had visited India in September 1973 and again in March 1983 for NAM summits.
He has also interacted with Nehru in New York and has hosted former Prime Minister Rajiv Gandhi and current premier Manmohan Singh at NAM Summits in Havana. Coming at a time when China is trying to make inroads into Cuba, Ansari's visit is being seen as an attempt to strengthen India's presence in Southern America.