Mr Dunne said that in its rush to break the story of Brian Lenihan’s illness, the TV station had “crossed a line that it didn’t need to cross”.
In a speech that underlined the importance of a free media, Mr Dunne also warned that “personal privacy must be protected in a civilised society”.
The former retail king, who is now a leading player in the fitness sector, is no stranger to media attention having famously been arrested for cocaine possession after going on a high-octane cocaine binge with a prostitute in a Florida hotel in 1992.
The incident eventually led to his removal from the family business.
“The state of the minister’s health is a very sensitive issue and you just have to look at this issue from a point of fairness and common sense.
“You have to say ‘hold on and lets hold this for a bit’. They (TV3) could have waited. A lot of people didn’t like the timing of the broadcast,” he said.
TV3 controversially broadcast news of Mr Lenihan’s cancer the day after Christmas, having given the father-of-two just 48 hours to inform any unaware family members.
Speaking at a seminar on privacy hosted by the Press Council in Cork city, Mr Dunne spoke candidly of his experiences of the press, saying he had never been “scared of the media” and had always spoken honestly. He said he could have hidden but he chose to face reporters.
“I was a newsmaker… Some of the news about me I didn’t like but unfortunately, it was nearly always true. I learnt that it [media interest] came and went and that in my personal life, it came and went too,” he said.
“I always took the good with the bad but I know that not everybody is able to do that.”
Mr Dunne said free media “is the banner of freedom in a democracy by its probing actions and presentation of alternatives”.
He said he had never refused a call from a journalist or refused to answer any question put to him.