The Iranian Greco-Roman wrestler defeated Parviz Nasibov of Ukraine 6-5 in the 67kg final.
Esmaeili had edged out Tokyo champion Mohammedreza Geraei in a playoff to book his ticket to Paris and the 21-year-old offered a glimpse of his form with a 9-0 rout of Cuban Luis Orta to move on to the final.
Orta had moved up after winning the 60kg gold in Tokyo but had to settle for bronze in Paris.
Iranian wrestlers Mohammadhadi Saravi and Amin Mirzazadeh have previously won a gold and a bronze medal in the 97kg and 130kg, respectively.
Iran has sent a total of 40 sports people to the Olympics in Paris this year who have won 6 medals so far, placing their country in the 21st spot in the medal tally.
Greco-Roman wrestling has been a blue-ribbon Olympic event ever since the first modern Games were held in Athens in 1896. It became a permanent fixture on the Olympic program in 1908.
MNA