An eyewitness said the attacker had been driving a services for communities van when he got out and beat a man to the ground in Yeaman Place, Fountainbridge.
He later got back into the vehicle and drove towards Merchiston, it has been claimed.
It is understood the number plate of the van involved in the incident matched that of a vehicle in the council’s fleet.
A council spokeswoman said: “The council takes this matter seriously and will investigate this incident fully and take appropriate action depending on the outcome.”
An eyewitness, who reported the incident to the council but wanted to remain anonymous, said he was “shocked” to see what appeared to be a council worker delivering the “brutal assault” late last Tuesday.
“Seeing someone getting a beating in the street is not unheard of in these parts but I was shocked when the attacker jumped in a council van and sped off,” he said.
“I was walking down Yeaman Place at around 11pm and could hear a commotion ahead – like shouting, yelling and thumping – but I couldn’t really see what was going on.
“There was a council van parked at the side of the road and as I got further down the street I saw a man wedged between parked cars who was getting a proper hammering.
“He was on the receiving end of quite a stiff kicking. He was pinned to the ground and was being repeatedly punched to the head.
“At one point the assailant stopped hitting him but the victim obviously said something he didn’t like and he started beating him again. It looked pretty serious because he was really going for him.”
The source added that after the assault ended the attacker got into an empty white Transit council van and drove off.
He said: “It was a white Transit van with services for communities on the side but the guy was wearing civvies. He was the only person in the van and sped off towards Merchiston. It was all over fairly quickly but the man was bleeding quite heavily from the nose and was puffy around both eyes.
“He picked himself up off the ground and looked a bit dazed and non-plussed.”
A police spokesman said they had received no reports of the assault.