"I've never said the government should apologise," Harriet Harman said after narrowly defeating five other candidates to replace John Prescott on Sunday.
"What I've said is I actually voted for the war on the basis that there were weapons of mass destruction and I was wrong on that," Harman told BBC Radio Four's Today programme.
All six candidates originally voted for the UK to join the US-led invasion, but during the closely fought campaign, she was the only one who said that she agreed with one of her rivals, backbench MP John Cruddas that her party should apologise over the war.
"I just think that if you are looking forward and you want to rebuild public trust and confidence, you have got to admit when you get it wrong," Harman also said during a hustings event broadcast by BBC Newsnight.
But when pressed during her interview to clarify her comments, she insisted that what she said was that "if I knew then what I know now, I wouldn't have voted for it."
"What I said was that we had to recognise the anger and bitterness that has been caused by Iraq, and we do, whilst at the same time strongly supporting our troops," Harman replied.
"How many times can I say it? I haven't asked anybody else to do anything – I've just explained what my position is," she said when asked again.
"I have not said I will press for a public apology from the government or the Labour Party," the new deputy leader later insisted when pressed further in an interview with BBC Two's The Daily Politics.
Harman, who is currently Justice Minister, was elected as deputy to Chancellor of the Exchequer Gordon Brown, who was endorsed to replace Prime Minister Tony Blair as leader at a special Labour conference convened in Manchester, north-west England.
But she is not expected to become also deputy prime minister, like Prescott, after Brown, who is set to become prime minister on Wednesday, appointed her as Labour chairperson, a cabinet post.
Speculation was that the current House of Commons leader, Jack Straw, would act in some capacity as deputy after running the chancellor's successful campaign.
Blair himself has continually refused to apologise for the Iraq war, despite being pressed by the media and anti-war colleagues on many occasions.