Not wanting to confront the person unarmed he had got his small, imitation pistol, tucked it into his waistband and pulled his shirt over the top to conceal it.
As the 13-year-old college boy was about to get on a bus Tuiomanufili confronted him about the smashed bus shelter windows and became aggressive.
The boy, fearing for his safety, got on the bus and grabbed a wall mounted fire extinguisher.
It was then Tuiomanufili lifted his top and showed the 13 year-old the handle of the pistol saying "I'm going to shoot you."
Police said the boy was fearful and believed Tuiomanufili would carry out the threat.
Realising police had been called Tuiomanufili walked home but as he went in the front door turned and pointed at the boy with two fingers forming a gun and said "I'm going to get you."
He was arrested soon after and the grey, plastic replica pistol was found hidden under a couch.
Tuiomanufili had admitted to police being in possession of the fake gun but denied threatening the boy.
For Tuiomanufili counsel Loiuse Elder said Tuiomanufili had got "the wrong boy" and as a result was very apologetic.
Judge Wainwright said the boy had "probably completely freaked out" especially when being confronted with a "pretend weapon."
She described Tuiomanufili's conduct as " disgraceful" and said Tuiomanufili should write to the boy explaining his actions and apologising.
Judge Wainwright sentenced him to 9 months supervision with a condition he undergoes counselling for alcohol abuse.