Chief Executive Carrie Lam held a press conference at 4 a.m. and said she was "angry" and "saddened" by the Monday's violence during which protesters rammed the glass facade of the Legislative Council (LegCo) building before storming into the main parliamentary chamber and vandalizing property.
Hundreds of policemen had to use tear gas to clear the building.
"I am very outraged and distressed and I strongly condemn it," she said, adding that she had reflected on the unprecedented events on the anniversary of Hong Kong's return to Chinese rule and was willing to communicate with all sectors including the city's youth, the South China Morning Post reported.
She compared the protesters' violence to a peaceful public march, also held on the day which marked the anniversary of Hong Kong's handover to China by the UK.
"We have seen two entirely different public scenes. One is a regular march on July 1. Regardless of the number of participants in the march, it was peaceful and generally orderly. This fully reflects the inclusiveness of Hong Kong society and the core values we attach to peace and order," Lam said at police headquarters.
"The second scene... is the extreme use of violence and vandalism by protesters who stormed into the Legislative Council building. This is something that we should seriously condemn, because nothing is more important than the rule of law in Hong Kong."
She added that the government would "pursue the lawbreaking behaviour to the end".
China, meanwhile, accused the protesters who vandalized Hong Kong's Parliament of "serious illegal actions" that "trample on the rule of law".
Beijing urged the city to investigate what it called the "criminal responsibility of violent offenders".
Monday's disorder followed weeks of protests over a controversial extradition bill, which critics have said could be used to send political dissidents from Hong Kong to mainland China. The protesters are demanding the withdrawal of the bill, Lam's resignation and the release of all those detained in clashes with the police in protests.
A spokesperson for the Hong Kong and Macau Affairs Office of China's State Council in a statement expressed support for the Hong Kong government and the police to handle the incident in accordance with the law and investigate criminal responsibility of offenders.
The office added that the incident infringes on Hong Kong's rule of law and called it a blatant challenge to the "one country, two systems" policy under which the city enjoys autonomy in some spheres.
According to the organizers of Monday's protests, around 550,000 people took part.
Although Monday's demonstration was not supposed to go near the area where the Parliament is situated, eventually a splinter group of protesters headed towards LegCo and started battering the glass and metal security gates.
After four hours, the protesters - many wearing black clothes, gas masks and at points protected by people shielding their identities with umbrellas - managed to storm the building, including the main parliamentary chamber, where they defaced property then fled before riot police moved in.
( With inputs from IANS )