But, in a statement, Patel defended the arresting officers' actions.
"The very nature of policing is dangerous and our primary role is to keep the community safe from harm," he said.
Police said the alleged 17-year-old offender, disguised with a cap and a bandana, entered the Northcote Bakery, armed with a large glass bottle about 4pm yesterday.
The teen then allegedly demanded cash from the 33-weeks pregnant worker, who was "felt threatened and shaken", police said.
"Police were called and officers went immediately to the scene. The officers comforted the victim and reviewed CCTV footage of the incident. They began searching the area and at the back of the Northcote shops they saw a man who fitted the description of the man in the CCTV footage," Patel said.
Police said a foot chase ensued down an alleyway and side streets for nearly a kilometre.
"Police at this time saw that he still held the bottle that had been used in the robbery," Patel said.
"As can be seen in the video, there were children around at the time and the two staff were faced with a large, armed and dangerous offender who had just carried out a robbery on a pregnant woman."
Patel alleged the offender "continued to refuse to comply with instructions to move his arms out from under him and continued to try and reach for something in his pockets and his waistband".
"It is a reality of policing that people will sometimes resist arrest in a violent and dangerous manner and when this happens our officers are required to use force to ensure both the public and our staff are kept safe," Patel said.
The 17 year-old was charged with robbery and will appear today in the North Shore District Court.