The attempted demonstration was to mark the 100th anniversary of the short-lived Belarusian People’s Republic of 1918-19, seen by the opposition as the foundation of an independent Belarus.
The anniversary is traditionally a day for opponents of President Alexander Lukashenko’s authoritarian government to try to rally.
Journalists at the scene counted at least 70 people taken away by police. The human rights group Viasna said five of its observers were among those arrested.
One of Belarus’s most prominent opposition figures, Nikolai Statkevich, was arrested outside his home as he headed to the gathering, said his wife, Marina Adamovich. She said he had been sentenced to 10 days in jail.