The demonstration is scheduled to continue on Wednesday and President Iván Duque says he is ready for a national dialogue.
The background to the protests is a bill on increased taxes.
At least 19 people have been killed, including 18 civilians and a police officer, and more than 840 people have been injured in clashes between protesters and riot police, according to official figures.
In addition, 89 people have disappeared, according to the country's human rights ombudsman, who is independent of the government.
Deeply shocked
Both the UN, the EU and the US condemn the violence against the government-critical protesters in Colombia, which is believed to have been strongly unjustified.
The UN High Commissioner for Human Rights says he is particularly deeply shocked by reports that police in the city of Cali have set fire to protesters on Tuesday night, which is said to have led to deaths and several injuries.
"What we can say clearly is that we have received reports, and we have testimonies, of excessive violence by the security police, firing, that sharp ammunition was used, that protesters were beaten and even arrested," said spokeswoman Marta Hurtado at the UN headquarters. in Geneva.
Withdrew reform - but protests have continued
President Iván Duque withdrew the criticized tax reform earlier this week and Finance Minister Alberto Carrasquilla has resigned - but protests have continued.
New mass demonstrations are planned to be held on Wednesday, where the demonstrators will demand a guaranteed basic income, that a proposed health care reform be withdrawn and that the riot police force ESMAD be disbanded.