A bishop who was stabbed at a Sydney church on Monday has said he is "recovering quickly" and forgives his alleged attacker.

In an audio message, Bishop Mar Mari Emmanuel also called for the community to remain calm.

Police say the attack, which was livestreamed and injured four people, was a religiously motivated terror act.

It sparked a riot outside The Good Shepherd Church, where angry supporters of the bishop had gathered.

A 16-year-old boy “ who was also injured “ has been arrested over the incident, but has not been charged with any offence. Authorities have repeatedly declined to state the suspected beliefs of the boy.

Earlier this week, Australian Security Intelligence Organisation boss Mike Burgess said authorities were investigating videos that allegedly captured the suspect yelling in Arabic and referencing "the Prophet".

In Bishop Emmanuel's four-minute clip, released by the church on social media on Thursday, he says he forgives "whoever has done this act".

"And I will always pray for you. And whoever sent you to do this, I forgive them as well in Jesus's mighty name," he said.

He added that he was "doing fine" and "there is no need to be worried or concerned".

'Do I stop coming to church?': Tensions run high in multi-faith Sydney

New South Wales Police have previously said the cleric is "lucky to be alive" after the stabbing, which occurred while he was saying mass at the Assyrian Orthodox Church, which is about 35km south-west of the city centre.

When graphic videos of the attack “ and the aftermath “ spread rapidly online on Monday night, they drew hundreds of people to church. There, violent unrest left two police officers injured, 10 police cars destroyed, and paramedics fearing for their safety.

Police have promised those involved will be tracked down and charged. They made their first arrest, a 19-year-old man, on Wednesday night.

With tensions running high, authorities and community leaders have been concerned about further "tit-for-tat" violence.

Bishop Emmanuel also used his public message to urge his supporters to cooperate with police.

"I need you to act Christ-like. The Lord Jesus never taught us to fight. The Lord Jesus never taught us to retaliate." (BBC)