The Iranian spokesman referred to the role of Singh in the economic development of India and in the expansion of ties between Tehran and New Delhi during his tenure.
He also extended his sympathies to the family of the late Indian prime minister and prayed for divine mercy on him, the Foreign Ministry’s website reported.
Singh, the first person of India's minority Sikh faith to take office as prime minister, died in New Delhi on Thursday at age 92.
A renowned economist, he was known as the father of economic reforms in India but was seen as a weak leader by many, including some within his party, the Indian National Congress.