Thousands of cars honked their horns throughout the capital, and many people were dressed in purple, Rowhani's campaign colour. Some even handed out purple balloons to the crowd.
"We said no to commander, we said no to mayor, (we chose) the courageous Rowhani," people chanted.
That was a reference to two defeated candidates, ex-Revolutionary Guards chief Mohsen Rezai and Tehran Mayor Mohammad Baqer Qalibaf, both hailing from the conservative camp.