Employees of Grodno Azot, Zhabinka Sugar Plant, as well as the Minsk Gear Factory on Friday demanded fair elections and an end to violence.
A former Soviet collective farm manager, Lukashenko is grappling to contain the biggest challenge in years to his rule of the country seen by neighbouring Russia as a strategic buffer against NATO and the European Union.
Protests were joined by workers from another industrial plants that are the pride of Lukashenko's Soviet-style economic model, including the Minsk Automobile Plant (MAZ) that makes trucks and buses.
The protesters accuse Lukashenko of rigging last Sunday's presidential election to win a sixth term. The president, alleging a foreign-backed plot to destabilize the country, has dismissed the demonstrators as criminals and unemployed.