Tasmania Police has defended actions taken by officers during the arrest of an alleged armed robber in Hobart on Wednesday morning.

The 20-year-old Berriedale man allegedly robbed the Guardian Pharmacy at Montrose at knife-point about 9.05am.

Tasmania Police Inspector Troy Morrisby said capsicum spray was used on the alleged offender, however, it did not subdue him.

Footage captured by a witness showing the arrest has circulated social.

In the footage, several police officers direct the alleged robber to get on the ground and drop the knife.

One officer appeared to punch the alleged robber in the head multiple times after being pinned.

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Inspector Morrisby commended the actions taken by police, saying the outcome of the arrest was "peaceful" and no one, including the offender, were seriously injured.

"Within those minutes, our officers are asked to make dozens if not more split-second decisions in regards to the way they react ... in this matter there was an excellent outcome," he said.

According to Inspector Morrisby, the alleged offender was checked a number of times after the arrest to see if they had sustained injuries.

"We've gone through appropriate steps post-arrest which is to see if that person required any medical attention ... they didn't require any medical attention," he said.

Inspector Morrisby said an independent review is always conducted into the use of force during police-related incidents.

Two police officers received minor injuries and have been treated.

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The footage also showed what appeared to be an undercover police vehicle used to disrupt the suspect.

The vehicle knocked the alleged robber to his knees where he discarded the knife, allowing police to subdue him.

Inspector Morrisby said it certainly wasn't standard practice to use a police vehicle this way, and that it was not something that police would necessarily train in.

"There are no clean rule books written for these situations, there's no clear guidelines written for every situation," he said.

In regards to the video, Inspector Morrisby said it was very easy for the public to make commentary on the actions of officers from their homes after an incident has occurred.

"It's very easy for people to make commentary in regards to the job police do on a daily basis," he said.

Inspector Morrisby said the investigation is ongoing and it is not known whether the alleged offender was under the influence of drugs, alcohol or whether they had a disability.

He said the way in which the alleged offender is presented in the video may be due to the capsicum spray used on them.

Officers involved in the incident were not armed with tasers, Inspector Morrisby said "It's not a practice where front-line members are equipped with tasers in those situations".