The protesters, who are demanding the immediate resignation of President Alexander Lukashenko, are said to have been stopped and dispersed by police.
Daily protests
Up to 30 people are said to have been arrested on Saturday, according to Viasna human rights center, reports the news agency AP.
Almost daily protests have taken place in the Belarusian capital since the heavily criticized presidential election, in which Lukashenko, who has been in power for 26 years, is suspected of manipulating the election result to his advantage, something he himself denies.
"Great and bright power"
The demonstrations have been met by heavily armed military and police, and several people have testified about torture and violence from the authorities.
Earlier this week, opposition leader Svetlana Tichanovskaya threatened the president with a nationwide strike if he did not resign.
She pays tribute to the protesters who went out on Saturday and calls them a "great and bright force".