During his bail application this week, an investigating detective said the teenager had previously spoken online about planning retribution against police as payback for his arrest in 2016 on other offences.

But the magistrate released the the 17-year-old, who cannot be named, on bail saying despite the concerning nature of his online comments and "justifiable fear" by police about what he might do, the posts were written 18 months ago and the boy had not been in trouble with the law since.

The release of the transcript comes after Police Minister Lisa Neville on Thursday condemned the decision to bail the teen, who allegedly attacked the 25-year-old police officer at Highpoint shopping centre in Maribyrnong on Boxing Day.

The detective and police prosecutor told the magistrate the teenager kicked the officer while the policeman was on his knees arresting another teen for allegedly shoplifting. They said the assault was premeditated and against a vulnerable target.

"He harboured a hatred towards police and he stated he had been biding his time," the detective told the court on Tuesday.

"He had been very angry towards police and wanted to get back at them, consistent with what he stated on Facebook."

Images of the police officer's blackened eye and bruised face were released on Wednesday by the Victorian Police Association to express its outrage over the leniency shown to the alleged offender.

The victim, 25, who has been in the force for five years, was surrounded by a group of young men before one sank his boot into the officer's face.

Ms Neville said Victoria Police had "strongly opposed bail in this case due to what they felt was an unacceptable risk to the community" and described the decision as "incomprehensible".

The teenager was on 12 months' probation at the time of the alleged assault and has a history of criminal offences including aggravated and attempted aggravated burglaries and car theft.

The accused teen, from the western suburbs, was arrested last week and charged with assaulting an emergency worker on duty, intentionally and recklessly causing injury, and common law assault. He appeared at the Children's Court last Friday before he was bailed.

Acting Premier Tim Pallas also called on the court to justify its bail decision, saying Victorians "expect a clear explanation and justification for the choices that the court is making, and I think they deserve nothing less than that".

Mr Pallas said the government was implementing more restrictive bail laws from July 1. He said applicants would have to demonstrate a "compelling case" about why they should get bail once the new laws are introduced.

But it was the Andrews government that amended bail laws for underage offenders in 2016, introducing a new section stipulating custody was the last resort.

Section 3B means the court has to take into account all other options before remanding a young person, including family, home, education, minimising stigma and the likely sentence they would receive if found guilty.

In a press conference on Thursday afternoon, shadow attorney-general John Pesutto said the government were "hypocrites of the year" for criticising the courts for applying the weakened bail laws they introduced themselves.

But rioting in youth justice centres, carjackings and home invasions, as well as the Bourke Street tragedy last year, meant the government came under more pressure and it announced widespread changes to legislation, including to bail.

One amendment means that bail for an accused charged with an aggravated burglary or carjacking would be refused, regardless of the person's age.

The amendments are not expected to come into place until July, although it's understood the Attorney-General is trying to push the changes through by April, with the change slowed by the need to implement more police and prosecutors, training for courts and more beds in custody.

The Coalition has promised to introduce tougher bail laws if elected in 2018.

Ms Neville said that reforms announced more than a year ago targeting youth offenders - including the provision of youth control orders, and so-called "Fagin's Laws" cracking down on those who direct youth offenders - could be used by police in coming months.