The Savetski district police station in Minsk imposed a fine on Rymashewski, co-chairperson of Belarusian Christian Democracy (BCD), on a charge of making a knowingly false report to the police.
The chief of the police station ordered Mr. Rymashewski to pay a fine of 1,950,000 rubels ($202).
Mr. Rymashewski is one of the first opposition activists to be fined under a recently enacted bill that allows the police to judge disorderly conduct cases.
The charge was brought against Mr. Rymashewski over a signature-collection event that was held near Kamarowski Rynak, a marketplace at the center of Minsk, on Sunday by BCD activist Maryna Khomich.
Ms. Khomich, chairperson of Belarusian Christian Democracy’s youth wing, is seeking to run in March’s city soviet elections.
Signature collectors phoned the police after people in civilian clothes approached them and started hurling insults and making threats. The plainclothesmen included the deputy chief of the Savetski district police station.
According to Mr. Rymashewski, the police never arrived. Nevertheless, the charge sheet against him claimed that a police detail had been dispatched to Kamarowski Rynak in response to his call.