The stabbing at Christ the Good Shepherd Church in Wakeley left Bishop Mar Mari Emmanuel and a priest hospitalised after a knife-wielding teen struck during a live-streamed sermon.
It was declared an act of terrorism on Tuesday, however the alleged attacker - a 16-year-old with a history of knife-related crime - is yet to be charged.
He remained under police guard in hospital and was likely to remain there for a number of days, NSW Police Commissioner Karen Webb told ABC Radio on Wednesday.
The incident met the criteria to be declared an act of terrorism, which granted police enhanced powers, but it remained to be seen if the teen would be charged with terrorism offences, she said.
The teenager's family have moved out of their home following intense media interest and threats of reprisal attacks on Islamic religious centres after the stabbing at the Assyrian Christian church.
"I think they've made a decision to move for the time being so they're not the centre of attention about this," Ms Webb said, adding their privacy should be respected.
A candlelight vigil outside the church went quietly on Tuesday night and there were no related incidents reported across Sydney, she said, however there remained a risk as emotions ran high.
"The community actually needs to come together and just really consider this, this is one person acting alone and this is not about one community versus another," she said.
Police were injured and paramedics sheltered in the church when a subsequent riot broke out as some tried to gain access to the attacker, who was being held inside the place of worship at the time.
"We believe that people not associated with the church have turned up as an excuse and become a riot that involved police," Ms Webb said.
Footage from CCTV, police bodycams and helicopters, as well as DNA testing of vehicles, was being used to identify those responsible for the riot.
The police presence would be bolstered across western Sydney and around places of worship for days as "combustible" conditions persisted, NSW Premier Chris Minns earlier said.
The public was being urged to come together and act reasonably.
"Take the heed from the civic and religious leaders of this state who are calling for calm and an absolute repudiation of all kinds of violence," Mr Minns told Seven's Sunrise program.
Footage of the attack and subsequent riots were widely shared on social media, where federal frontbencher and Sydney MP Tanya Plibersek warned lies were being used to divide a reeling city.
"We know there are people deliberately trying to stoke division on social media ... switch it off if you can," she told ABC TV.
Threats were made against Lakemba Mosque, one of Australia's largest Muslim places of worship, following the church attack.
The Lebanese Muslim Association shared footage of Lakemba Mosque Imam Sheikh Yahya Safi condemning the attack on Tuesday.
"This is against our religion, we don't accept it in any way, and it is childish act," he said in the video message.
"We need our society to keep this tranquillity, to live together in safety."
The Australian Federation of Islamic Councils also condemned the stabbing as an atrocious act.
"Such an act of brutality stands in stark opposition to our cherished values of peace, empathy, and reciprocal respect," it said in a statement, urging community members to help with the police investigation.
