The father of Australian tennis star Bernard Tomic said Wednesday he wished now that he had "really punched" his son's French training partner.
John Tomic received an eight-month suspended jail sentence on September 6 for headbutting Thomas Drouet, breaking his nose and knocking him out in a May assault outside a Madrid hotel.
Tomic denied the charges in court and said he acted in self-defence.
"I know that I didn't do that," Tomic senior told the Sydney Morning Herald. "And I am just now regretting why I didn't punch him, when I see this campaign against Bernard, against me.
"I'm really regretting why I didn't punch him now, because I think that he deserved that. I know that I would be in more trouble in the future, but when I see how he has been lying."
Australian media this week published claims from a Drouet diary that Tomic had hit his son in the face and drew blood in Monte Carlo before heading to Madrid.
"Never. It never happen that I touch my son, my kids. I am very proud father and my kids love me," he told the daily.
But the disciplinarian admitted to arguments and racquet smashing.
John Tomic, 49, would not confirm in the interview if he intends to appeal the Madrid court decision, but he maintained his innocence on the headbutting charge.
"Look, I have to take consequences about court, about (Drouet's) story, and I will accept the decision of court and what I have to do, but I didn't do that.
"It was collision head to head -- when he hit me I just grabbed him and it was collision head to head."
Following the clash, the Australian number one's father was banned from attending ATP events.
But he maintained that his professional relationship with his son was healthy and productive, and will continue unless the world number 50 asks him to step aside.
Father and son are due to be reunited this week to prepare for hardcourt events in Bangkok, Beijing and Shanghai.