"With a dedication to national and Islamic culture and a deep understanding of the conditions and concerns of society, this artist created fine social documentaries during his artistic life and his resume is filled with memorable works," wrote Rouhani in a message on Monday.
"Hereby, I offer my condolences to the family of the deceased and his fans and followers, especially to the artistic community of the country."
At the age of 79, Sainai succumbed in his battle with COVID-19 and died at Tehran’s Amir Alam Hospital on Saturday.
Sinai's work was influenced by documentaries and focused on social and artistic subjects.
"Bride of Fire" is among his best-known movies, and has won multiple awards in both domestic and international film festivals.
He was the first Iranian film director to win an international prize after the Islamic revolution in Iran and has been awarded the Knight's Cross of the Order of Merit of the Republic of Poland.