In a message to the Qatari emir on Sunday, President Pezeshkian expressed sympathy to Sheikh Tamim, the Al Thani family, and the government and people of Qatar over the passing of the country's former ruler.
The Iranian president said the late Sheikh Hamad played a significant role in expanding the brotherly relations and friendly cooperation between the Islamic Republic of Iran and the State of Qatar during his years in office.
Pezeshkian added that the former emir's efforts to deepen bilateral ties would be remembered with respect and appreciation by the people of both countries.
He also commended Sheikh Hamad's lifetime of service to Qatar and his contributions to promoting closer relations between Tehran and Doha.
Concluding his message, the Iranian president prayed for God's mercy upon the late former emir and wished patience and fortitude for Sheikh Tamim, the Al Thani family, and the people of Qatar during their time of mourning.
Sheikh Hamad bin Khalifa Al Thani died at the age of 74 on Sunday.
Qatar has announced a four-day period of public mourning starting Monday, with work suspended at government agencies and public bodies and flags to be lowered to half-mast.
Sheikh Hamad, who ruled Qatar from 1995 to 2013, was a key architect of the energy-rich country’s development.
In 2013, he handed over power to his son and heir apparent, Sheikh Tamim bin Hamad Al Thani, who was then 33, in a rare abdication by a hereditary Persian Gulf Arab ruler.