President Ivan Duque had urged citizens to reject violence and stereotypes about demonstrators and police alike.
Riot police at nightfall emerged from the Congress building and fired tear gas and stun bombs at the thousands of protesters gathered in the capital's central Bolivar Plaza.
As they left the square, protesters shattered glass benches on their way.
The sometimes violent demonstrations began in late April, initially fuelled by outrage at a now-cancelled tax plan.
Protesters' demands have expanded to include an end to police violence, economic support as the COVID-19 pandemic affects incomes, and the withdrawal of a health reform.
Duque has offered dialogue, but many protesters doubt government promises will lead to change and talks with union and student leaders have so far proved fruitless.