A South Australian Liberal candidate is asking for witnesses to come forward after she alleged that she was assaulted on the campaign trail yesterday.

Jassmine Wood, a candidate for Hindmarsh in Adelaide's western suburbs, says she was outside a shopping centre with a volunteer when they were approached by two men who were critical of the Liberal Party's border protection policies.

Ms Wood says the men punched her and her volunteer in the face.

"I got hit in the side of the head. My campaign volunteer was actually down on the ground with somebody sitting on his chest really hitting him in the face," she said.

"My poor volunteer who was on his first day of the campaign trail got punched in the face many times."

Ms Wood says she has given police a description of the men.

Police say they are investigating the incident.

Ms Wood wants witnesses to come forward to help police charge the men responsible.

"One was extremely tall so I'd estimate about 195 centimetres - that was obviously the violent man," she said.

"He was also with a friend that was slightly shorter than me so both caucasian, dark hair, one with glasses.

"There was a lot of people watching, there was a lot of people who saw it but unfortunately most people just got in their cars and drove off after the fight had ended so we're looking for people out there who may have seen what happened so we can actually get some witnesses because we would like to press charges."

Charges were laid, but later dismissed in court.