Lukashenko defied an ultimatum to surrender power by midnight, challenging his opponents to carry out a threat to paralyze the country with strikes, nearly three months after his disputed election victory unleashed mass protests.
If sustained, the strikes could open a new phase in the crisis, testing whether the opposition has the mass support it needs to bring enterprises across the country of 9.5 million people to a halt.
The opposition has mounted some strikes at state-run factories previously, but they were not sustained.
Belarusian media reported groups of strikers at many major state-controlled enterprises. However, the prime minister's spokeswoman said all the major industrial companies were working normally.
Many shops, cafes and restaurants were closed in central Minsk. Hundreds of university students took to the streets in the capital, clapping and chanting as passing cars tooted their horns in support.