Some 500 people rallied in the Belarusian capital, Minsk, on February 28 to demand that the government scrap a new regulation, which protesters say imposes an unfair burden on small private businesses.
The unsanctioned rally was the largest protest in recent years in Belarus, where the authoritarian government has shown little tolerance for dissent.
Police, however, did not interfere and the demonstration ended peacefully.
The regulation, introduced this year, stipulates that small private businesses should obtain certificates guaranteeing the quality of their products.
Business owners complain the certificates are expensive and take weeks to obtain.
The Associated Press quoted Minsk businessman Ales Makayev as saying "why do these certificates cost 5 euros in Europe and in Belarus we need to pay $200 or $100 and spend 20 days to get them?"
The regulation appears to be part of government efforts to increase budget revenues amid an economic crisis in Belarus.
The country's economy contracted 4 percent last year and the currency has fallen 40 percent since the beginning of 2015.
Minsk to ask International Monetary Fund for a loan of $3 billion.