Australian tennis star Nick Kyrgios has admitted assaulting an ex-girlfriend but avoided a criminal conviction.

The 27-year-old's guilty plea in a Canberra court came after his lawyers failed to have the charge dismissed on mental health grounds.

Mr Kyrgios pushed Chiara Passari onto the pavement during a row in Canberra in 2021, the court heard.

The magistrate called the incident "a single act of stupidity or frustration" when sparing him a criminal record.

Mr Kyrgios released a statement after the ruling saying he was grateful to the court for dismissing the charges without conviction.

"I was not in good place when this happened and I reacted to a difficult situation in a way I deeply regret," he said.

"I know it wasn't OK and I'm sincerely sorry for the hurt I caused."

Agreed facts tendered to the court say Mr Kyrgios pushed Ms Passari after she stopped his car from driving away while they were arguing on 10 January 2021.

Ms Passari reported the incident to police the next month but did not make a formal complaint. The couple reconciled and resumed a relationship, but after they broke up, Ms Passari made a formal complaint in December 2021.

Mr Kyrgios' lawyer argued his client had been trying to de-escalate the fight by calling an Uber, and had repeatedly tried to "lawfully" move Ms Passari away from the car.

"It is in that context and the frustration that resulted, that my client reacted and the offence occurred," Michael Kukulies-Smith said.

The court heard Mr Kyrgios had sworn at Ms Passari and told her to go away. He then put his hands on her hips and moved her an arms length from the door, but Ms Passari stepped back.

The tennis star then said: "I'm serious. I'm going to…" before pushing Ms Passari in the shoulder, causing her to fall.

Ms Passari felt some pain and later noticed grazing on her knee, the court heard.

The court heard Mr Kyrgios apologised the next day - an act that showed he accepted responsibility for his actions, his lawyer said.

Mr Kukulies-Smith also told the court on Friday there was: "a relationship between the mental health and the offending - even though he no longer suffers it to the same extent today."

Mr Kyrgios' psychologist Sam Borenstein told the court the tennis player's mental illness was "recurrent" and he had suffered from thoughts of self harm - but his condition had been improving.

When sentencing Mr Kygrios, Magistrate Beth Campbell said he had been "a young man trying to extricate himself from a heighted emotional situation".

"You acted in the heat of the moment," she said.

"I am dealing with you in the same way I would deal with any young man in this court. You are a young man who happens to hit a tennis ball particularly well."

She told Mr Kyrgios that references from family showed he had a lot of "love and support" around him.

The tennis player arrived at court on Friday on crutches following recent knee surgery. An injury forced him to withdraw from the Australian Open last month.