Road-blocks resumed overnight as protesters called on the government to resign amid corruption allegations.
Anti-government demonstrators formed roadblocks in Sofia on Friday evening in the 30th consecutive day of protest in the country.
Around 5,000 demonstrators gathered in the centre of the Bulgarian capital in spite of the rain shouting "Mafia!" and calling on the government of Prime Minister Boyko Borissov to resign.
Rallies took place in other five towns, including Varna and Plovdiv.
Police had initially dispersed the demonstrators and dismantled the camps they set up on Friday across the main roads of Sofia.
The Interior Ministry then assured that traffic had resumed at "all crossroads that had been blocked" and that new traffic obstacles would no longer be tolerated.
But on Friday evening, the demonstrations blocked again three key road-intersections, using street furniture and trash cans.
Police said 12 people were briefly detained.
During the past month, thousands of people have been taking part in protests every evening demanding the resignation of the government of Boïko Borissov, who's been in power since 2009, accusing it of corruption.
On Wednesday, Borissov offered to take a step back in order to give the executive a chance to hold out until the legislative elections of March 2021, but his majority renewed their support the next day.
Protests have also been taking place against chief prosecutor Ivan Geshev, after heavily armed officers raided on July 7 the offices of President Rumen Radev, a vocal critic of the ruling party.