An ambulance officer has undergone surgery after a "disgusting attack" in which he and a colleague were assaulted and their ambulance rammed while going to the aid of a patient in Melbourne's north.

Key points: Paramedic kicked, punched, knocked to ground

Paramedic kicked, punched, knocked to ground Other paramedic hit when she went to his aid

Other paramedic hit when she went to his aid Attacks called 'disgusting, gutless'

Attacks called 'disgusting, gutless' Violence will not be tolerated, Ambulance Victoria says

The paramedics were called to Hobbs Crescent in Reservoir about 6:30pm on Thursday when they were set upon by three people.

They were trying to care for a disoriented elderly man, when three bystanders, who had initially talked to the man, became aggressive.

One paramedic suffered a suspected broken foot, cuts and bruises after he was kicked, punched and repeatedly knocked to the ground by a man and two women.

He underwent surgery this morning.

Another paramedic was struck on the head when she went to the aid of her colleague.

The attackers then got into their car and rammed the ambulance before speeding from the scene.

Police had to take the patient to hospital.

Mick Stephenson, the acting general manager of emergency operations at Ambulance Victoria, said they would not tolerate violence, threats or abuse towards paramedics.

"It's disgusting. This a gutless attack on paramedics as they were in the community going to the aid of a patient," Mr Stephenson said.

He said they were not sure what provoked the attack.

"In this particular case we think the three people might have been drug- or alcohol-affected," he told 774 ABC Melbourne.

"Speaking to the paramedic involved this morning he seems to not really know what set it off.

"They'd walked away for a moment and came back, and they came back quite aggressively. So it was unpredictable and unprovoked."

Victoria Police is investigating the incident.

Attacks on paramedics an increasing phenomenon

Mr Stephenson said there was a "significant act of violence" against a paramedic every day and the number of assaults are under-reported.

"A lot of paramedics will tolerate this stuff and ignore it. I don't think you'd tolerate something to this extreme but they do tolerate aggression reasonably frequently," he said.

"It is an increasing phenomenon. It's something we're increasingly concerned about.

"Our number one priority really is to provide a safe workplace for our guys and at the moment that's a pretty difficult thing to do when these sorts of things are happening."

Mr Stephenson said Ambulance Victoria has a close relationship with police who regularly helped paramedics on duty.

However, he said, with more than 1,000 cases a day and half of them at night it would not be practical to have officers escort paramedics to every job.