However, Victoria's Attorney-General, Martin Pakula, later said police prosecutors did not ask the court for a custodial sentence.

The Acting DPP, Gavin Silbert, QC, lodged the appeal on the basis that the sentence imposed is "manifestly inadequate".

The teenager was on probation at the time of the attack on the police officer and prior to being sentenced for the assault he was controversially released on bail again.

The decision sparked a barrage of attacks from state government figures and compelled the children's court to take the extraordinary step of releasing an audio transcript detailing the reasons why the teenager was bailed.

An investigating detective said at the time 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 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.

Within days, the teenager was back in police custody for breaching his bail conditions.

He walked free earlier this month after serving less than a month in custody.

The DPP appeal comes weeks after the police union slammed the no-conviction sentence.