Hong Kong Chief Executive CY Leung has warned pro-democracy activists not to return to the streets following the latest outbreak of violence.
His comments come after some of the worst clashes between protesters and police since the pro-democracy demonstrations began two months ago.
Police armed with pepper spray, batons and water hoses cleared activists from Lung Wo Road in the Admiralty district.
Government offices were briefly shut on Monday.
In another development, prominent student leader Joshua Wong announced on Monday that he and two others were beginning a hunger strike to demand renewed talks with the Hong Kong government.
“Living in these troubled times, there is a duty. Today we are willing to pay the price,” the students said in a statement.
Student leaders opened talks with government negotiators in October but they failed to achieve an agreement and discussions have not been resumed.
Earlier, in a move which prompted fears of further violence, an injunction was granted to clear an area just west of the main protest site in Admiralty.
“From this day on, the police will take resolute action when carrying out their duties. I call on the students who are thinking of returning to the occupation area tonight not to do so,” Mr Leung said.
“Don’t mistake the police tolerance as weakness.”
Protesters want the people of Hong Kong to be allowed to choose their leaders in the 2017 elections without intervention from Beijing.
The Chinese government has said it will allow direct elections, but candidates for the post of chief executive will be screened first.