The decision to let a teenager who kicked a police officer in the head at a Melbourne shopping centre walk away from court without a conviction shows there are gaping holes in the state's sentencing laws, the police union says.

The teen was on parole when he attacked the policeman at Highpoint Shopping Centre on Boxing Day.

The Police Association said it was furious after he received nine months' probation at a Children's Court hearing last week.

"If you're allowed to target police officers and get away with it, effectively we're green lighting crime in Victoria," secretary Wayne Gatt said.

"An unprovoked attack on a police officer in Victoria is serious and it should be met with a conviction.

"A few people in the community will rightly question this."

But Victoria's Attorney-General, Martin Pakula, told 3AW that police prosecutors did not ask the court for a custodial sentence.

Mr Gatt said he was not sure why that's the case.

"It's not the usual practice in the children's court for sentencing submissions to be made, despite the fact that it is open to prosecution to do that," he said.

"But we shouldn't have to.

"Some facts and circumstances should speak for themselves and this is one of those cases where it's as plain as the nose on your face."

'You could drive a truck through sentencing laws'

Sentencing reform and bail laws have become a key issue for the Andrews Government, as it fights to establish its law and order credentials before Victorians head to the ballot box in November.

Tougher bail laws will come into effect in July this year after passing State Parliament last year.

The policeman was attacked at the popular shopping centre on Boxing Day. ( ABC News )

Earlier this month Police Minister Lisa Neville criticised a Children's Court for granting the teenage attacker bail.

She called on the court to explain the reasoning behind its decision.

"Just like I have to justify decisions I make, so too should the courts back to the community," she said at the time.

Mr Gatt said Victoria's sentencing laws were in desperate need of reform.

"You could drive a truck through some of them," he said.

"Magistrates do a hard job but so do police officers, and police officers in this state deserve to go home the way they come to work, and that's safe and sound, and we need the courts to support us in that endeavour.

"It chips you away slowly when you see case after case in the courts and you see repeat outcomes."