The Victorian Premier is urging police to appeal a Children's Court decision to free a teenager who kicked a senior constable in the face.

The 17-year-old refugee, who escaped conviction, was on probation at the time - and the police union is furious.

First a policeman was kicked in the face on Boxing Day then fell victim again when the violent criminal received a soft sentence.

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

View photos The policeman got a black eye. Source: 7 News More

The 17-year-old from Point Cook is a Sudanese refugee, and attacked the senior constable because his 15-year-old cousin was being arrested at Highpoint Shopping Centre.

Last week a Children's Court magistrate freed him without conviction, instead sentencing him to nine months' probation.

It has been revealed the teen wrote an apology letter to the officer, saying: "I feel really bad and really remorseful and really sorry for what I did. I didn't really realise it could affect his job".

The prosecutor did not make a submission about what sentence he should receive.

View photos The 17-year-old allegedly attacked the police office. Source: 7 News More

The magistrate said: "you have already served a month in custody. That is a very significant factor for me. It's really significant that you've got the VCE to start".

"An unprovoked attack on a police officer is serious and it should be met with a conviction," Mr Gatt said.

An earlier hearing was told the teenAGER had links to gang members and had threatened police online, vowing he would send an officer to hospital in retaliation for an arrest in 2016.

View photos The teen escaped conviction after allegedly doing this to the police office. Source: 7 News More

"Prosecutors are free to appeal both the issue of the conviction and or the nature of the sentence imposed," Premier Daniel Andrews said.

"I do in fact hope that they have a very close look, a very close look at this case."

Police will refer the matter to the DPP to consider an appeal.