Protesters brought together by the Alliance for Serbia, a loose grouping of 30 opposition parties and organizations, wore badges reading "It has started" and chanted "Vucic thief" in the eighth straight weekly protest by the grouping. Previous rallies have attracted similar-sized crowds.
"The only demand we have is that this evil (regime) goes away," said Branisalv Trifunovic, an actor who addressed the crowd as he had done in previous weeks. "We want elections, but freedom must come first."
No-one at Vucic's office could be reached for comment. The President previously said he would not bow to opposition demands for electoral reform and increased media freedom "even if there were 5 million people in the street," but said he was willing to test his party's popularity in a snap vote.
The latest protest follows a visit to Belgrade on Thursday by Russian President Vladimir, welcomed by tens of thousands of people bussed in from all over Serbia.
"I came here to express my dissatisfaction with the ruling elite," said Ljiljana Zivanovic, a 64-year old pensioner. "They (SNS and Vucic) control all media, I am sick of all the corruption going on."
The protests have spread to other cities in Serbia and on Friday were held in Novi Sad, the second-largest city, the southern city of Nis and several other towns, though numbers outside the capital remain small.
"I came here to protest because there is no state any more. All power is concentrated in hands of one man," said Luka Tripkovic, who is studying for a doctorate at the Faculty of Fine Arts in Belgrade.