Violence at the Legco building crossed the red line of peaceful Hongkongers, the pro-establishment camp says.
But pan-democrats said the government ignoring protesters' demands has led to an outburst of anger and pushed the city toward an unprecedented crisis.
The Democratic Alliance for the Betterment and Progress of Hong Kong said some "extremely violent" people used hard objects and a trolley to attack the Legco building, causing glass to shatter in multiple locations.
It issued its "strongest condemnation," saying such behavior seriously damaged order in society and the rule of law.
"They committed serious crimes and turned their backs from peaceful protests, a right guaranteed by the Basic Law. But they completely crossed [the red line] for Hongkongers who uphold peace," the DAB said.
It hoped all sectors would condemn the violence and "terror" to send a clear message that such action would not be tolerated. It thanked officers for exercising restraint and supported police prosecution of the violence.
Forty two pro-establishment lawmakers, except Legislative Council president Andrew Leung Kwan-yuen, issued a joint statement condemning the action.
"We urge the pro-democracy lawmakers to differentiate right from wrong and to condemn these extremely violent people, in order to defend the rule of law," it stated.
Bar Association chairman Philip Dykes said he was disappointed by protesters.
It was ironic to attack Legco, which is responsible for making laws, in the name of defending rule of law, he said.
The Hong Kong Police Inspectors' Association issued an open letter to members, strongly condemning protesters' splashing of liquid at officers. "Their action constitutes serious offenses and police will get to the bottom of things," it said.
It hoped the injured policemen would recover soon and that everyone with the force will stay united.
Former police commissioner Andy Tsang Wai-hung said protesters blatantly ignored the law. Concerning police action in previous protests, he said it is not necessary for police to be investigated by an independent inquiry, saying it would be a waste of time as compared to using established channels.
The Civic Party said Chief Executive Carrie Lam's ignorance of public opinion led to an "outburst of people's grievances" yesterday.
The clashes were sparked by discontent and the young people's desperation stemmed from Lam turning a blind eye to public opinion, which has "pushed Hong Kong toward an unprecedented crisis," it stated.