She went after the perceived front-runner during a leadership debate Saturday, questioning whether he has any real understanding of the problems facing middle-class Canadians.
Trudeau responded that his privileged background isn't an issue, what matters is his commitment to public service.
Hall Findlay was booed by some in the debate audience and was widely criticized on social media for the aggressive questioning.
She said she was trying to question Trudeau about whether his experience qualifies him to be leader.
After the debate, Hall Findlay said her comments were not personal and on Sunday she went further by posting an apology on her website.
"There are some who believe that I overstepped a line in the leadership debate," the statement said. "To Justin, his family and to those who were offended, I apologize."
"My comments were not meant to be personal, in the sense of being in anyway a comment on Justin’s character – indeed, I have the greatest respect for Justin’s passion, enthusiasm and commitment."
The statement goes on to stress Hall Findlay's accomplishments and some of her policy positions.
Trudeau's campaign didn't respond to the apology.
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