Health Secretary Wes Streeting told how he was “shocked and sad” by a video which appeared to show fellow MP Mike Amesbury repeatedly punching a man on the ground.
But the Cabinet minister stressed that he was not seeking to “excuse or justify” the alleged incident.
The police needed to investigate it, without giving any special treatment to Mr Amesbury because he is an MP, he added.
Then, the Labour Party and Mr Amesbury could decide whether he should quit as MP for Runcorn and Helsby.
Mr Streeting told Sky News: “It’s right that both the Labour Party have suspended Mike Amesbury while the investigation takes place and crucially that we give the police the space to do their work and decide what action if any needs to be taken.
“I’m shocked and also feel really sad because this is not something I would have expected from Mike.
“When you work with someone closely and you like someone very much it’s hard to see the image flash up on the screen.”
But he added: “I don’t want to in any way excuse or justify the behaviour and I don’t know the context obviously and it’s right that the police do their work and treat Mike as they would anyone else.”
He described Mr Amesbury as a “hard-working, affable decent parliamentarian who stands up for his constituents”.
He added: “That doesn’t in any way explain or excuse what we are seeing on the screen now.”
Pressed whether he should resign, he added: “It’s important that the police are given the space to do their work, decide what action needs to be taken and it’s right that the Labour Party has suspended him while that happens.”
Asked again whether he should resign: “That’s the sort of judgement that needs to be reached when we have got all of the fact available to us.
“It’s not my place given that I’m not in possession of all the facts to be judge, jury and executioner on this case, that’s why we have got the police doing their work.
“We will wait to see what their investigation turns up, it’s for the police to decide what action needs to be taken in terms of their lines of inquiry, and off the back of that it’s then for the Labour Party and indeed Mike Amesbury to decide what the approriate next steps should be.”
Sir Keir Starmer on Monday also described the video footage as “shocking”, as he defended Labour’s decision to suspend him.
The Prime Minister said the party had “moved very swiftly” to respond after the footage emerged.
Mr Amesbury was suspended by the party and lost the Labour whip on Sunday after a clip was published by MailOnline in which the Runcorn and Helsby MP is apparently seen continuing to hit the man lying on the ground as people nearby shout “Stop it”.
Cheshire Police confirmed a 55-year-old man had been voluntarily interviewed under caution in relation to the incident after officers were called to reports of an assault in Frodsham at 2.48am on Saturday.
“He has since been released pending further inquiries,” the force said.
CCTV published on Sunday captured two men standing facing each other before the man purported to be Mr Amesbury punched the other and continued hitting him on the ground.
It is not clear from the video what happened in the moments beforehand, but The Times reported the two men had been involved in a “heated” discussion about plans to close a bridge in Mr Amesbury’s constituency for engineering works next year.
There were also reports that the dispute involved the winter fuel payments, which the Government has axed for tens of millions of pensioners.
It comes after different footage posted on social media on Saturday appeared to show the MP shouting and pointing his finger at a man lying in the street.
“You won’t ever threaten me again, will you? You won’t ever threaten me again will you?” he appeared to say.
Mr Amesbury said on Saturday that he will “co-operate with any inquiries”, but was “determined to remain an open and accessible MP for our community” after the initial footage circulated online.
He said in a statement: “Last night, I was involved in an incident that took place after I felt threatened on the street following an evening out with friends.
“This morning, I contacted Cheshire Police myself to report what happened during the incident.”
Shadow health secretary Victoria Atkins said the video footage was “shocking” and it was “disappointing” that it took some time for Labour to act and suspend Mr Amesbury after.”
