For the second day in a row, hundreds of citizens gathered in front of the presidency building to express their support for the head of state.
Dissidents are demanding the resignation of Prime Minister Boyko Borissov and Chief Prosecutor Ivan Geshev.
"Bulgaria is not owned by the oligarchs - it is for all of us. We are here to demand fair elections and machine voting, "the president added.
Supporters of Democratic Bulgaria and the BSP are expected to join again after 18:00.
An hour later, a second protest, organized by GERB, will take place on Dondukov 1, in which party activists from all over the country will take part. The party said it expects nearly 10,000 people to join the pro-government rally, most of whom were taken by bus from the province.