Charles Clarke has apologised for the personal attack he made earlier this month on Gordon Brown.
Mr Clarke addressed at a Fabian Society fringe meeting on Sunday
The former home secretary said he had not behaved in the "best and most advised way" in making the comments.
And he believed any leadership debate should have been delayed until there was a vacancy and a contest.
Mr Clarke had accused the chancellor, in a newspaper interview, of "absolutely stupid behaviour" during the row over Tony Blair's leadership.
He said Mr Brown - who is widely expected to take over as Labour leader - was a "control freak", who lacked confidence and could not manage people in a "collegiate" way.
He said Mr Brown needed to "prove his fitness" to be prime minister.
Asked at a Fabian Society fringe meeting on Sunday if the recent leadership row had lent colour to politics or turned voters off, Mr Clarke said people would judge the party on the "way it conducted itself".
But reasoned debate had broken down in the past "two or three weeks" due to a "dislocation" in the party, he added.
"People behaved, including myself, in ways that were probably not in the best and most advised ways," Mr Clarke told the meeting.
He added: "We should not have a discussion about the leadership question until there is a vacancy and a properly organised leadership campaign."
But Mr Clarke also urged the party not to wait until a leadership contest to debate future policy direction.
He said there were no "fundamental" differences in the party on ideology, but it had to work out what it wanted to do in the rest of its third term, and how to respond to new challenges such as the environment.
"We have to have a discussion that is very difficult to do in the media environment there is today.
"But the price of not having that discussion is worse than the price of having that discussion," Mr Clarke told the meeting.