NSW Police were patrolling Eddie Ward Park in the inner-Sydney suburb of Surry Hills on Monday when they came across a group of teenagers.
What happened between then and the moment a teen switched on his phone camera is unclear, but what went down next was captured on film.
The group and the three officers argue, before a 16-year-old boy can be heard saying “I’ll crack ya across the jaw, bro”.
The male police officer then walks towards the boy and orders him to turn around, holding his hands behind his back.
The officer then kicks the legs out from under the boy causing him to fall to the ground face first. Two female officers help to hold him down as he is handcuffed.
The teen, who cannot be named under NSW law, was treated for minor injuries at St Vincent's Hospital before being released without charge.
A family member said in a post on social media that the teenager had sustained a bruised shoulder, cuts and grazing to his knee, face and elbow and chipped teeth, and they were awaiting the results of x-rays, NITV reported.
"That's just appalling".
The constable involved, who has been in the police force for three years, has been placed on restricted duties while a review is carried out.
"An investigation into the circumstances surrounding the arrest is now underway by officers attached to the Professional Standards Command," a police statement said.