The turnout was the largest in a long time in the student-led protests against the country's government and president. 77 people were arrested and several were injured after clashes with the police, according to the authorities. 48 police officers are also said to have been injured, one of them seriously.
Vucic accuses the demonstrators of creating "terror" and threatens with more arrests.
Serbia has won, and it is not possible to defeat Serbia through violence as some wish, said Vucic in a speech to the public.
There will be no new elections until the end of 2026, he added.
The demonstrations have been recurring since the serious accident at a railway station in the city of Novi Sad in November last year, when parts of the roof collapsed and 16 people were killed.
We want elections, chanted the crowd that gathered in central Belgrade.
Saturday's protests became unusually rowdy. In clashes, demonstrators threw pyrotechnics at the police, who responded with tear gas and batons.
According to an independent organization that maps public gatherings, around 140,000 participated, while according to the police's estimate it was 36,000.