It comes after the territory’s deputy leader called off talks with student leaders scheduled for Friday.
Carrie Lam said the students’ refusal to end their protest had made “constructive dialogue” impossible.
The protesters, demanding full democratic elections in 2017, paralysed parts of Hong Kong in recent weeks.
Throughout the week only a few hundred protesters, mostly students, remained on the streets around the financial and government district of Admiralty and in Mong Kok north of the harbour.
But after the talks were cancelled, leaders of the student movement called on supporters to return to the streets.
“Come to occupy the road outside the public headquarters, come bring your tents to show our persistence on long term occupy action,” said Joshua Wong, the 17-year-old founder of the Scholarism movement.
The BBC’s Juliana Liu in Hong Kong says the activists are hoping a new show of strength will be enough to sustain the movement.
“We are now planning on further action for escalating [the campaign] if the government keeps denying the meeting,” said Alex Chow, secretary general of the Hong Kong Federation of Students (HKFS).
Once again the protest was entirely peaceful and good-natured, with speeches, applause and a bit of singing. But this was a rally on a Friday night in response to a call for a show of strength – oughtn’t it to be ginormous, rather than just big?
Some estimates put the number at 10,000 or more but that’s still a long way short of the scale of the protests at their peak. Hardly resounding proof of city-wide support for the pro-democracy fight and disruption it’s causing.
But, if nothing else, neither is it small enough in scale to give the Hong Kong government what it so badly wants. This is not yet a movement that has run out of steam. The stalemate continues.
The protesters want to be able to directly elect Hong Kong’s leader, the chief executive, in the 2017 election.
China has said that, under Hong Kong law, voters will be able to vote freely but from a list approved by a nominating committee.
Ms Lam has accused the students of “undermining trust” in the proposed talks by repeatedly calling people out to protest.
“The dialogue cannot be deployed as an excuse to incite more people to join the protest,” she said. “The illegal occupation activists must stop.”
Democracy ‘a right’
In a separate development on Friday, Taiwan’s President Ma Ying-jeou used his National Day speech to urge Beijing to move towards democracy, voicing support for Hong Kong’s protesters.
Mr Ma said that as China became more prosperous, its people would want more democracy and the rule of law.
“Such a desire has never been a monopoly of the West, but it is the right of all humankind,” he said.
Taiwan – which Beijing views as a breakaway province but which has been governed separately since 1949 – has been watching developments in Hong Kong closely.