Alex Salmond came under fire from opposition leaders about the "crisis" in hospital A&E units.
The attack came after public spending watchdogs Audit Scotland found almost 104,000 people waited beyond the standard four-hour target in 2012-13, compared with about 36,000 in 2008-9.
The proportion of people being seen within the four-hour target fell from 97.2% at the end of 2009 to 93.5% by December last year, the report revealed.
Labour leader Johann Lamont said the First Minister had promised action on A&E waiting times last year but added: "Those waiting more than four hours for treatment has tripled on his watch."
She demanded: "When will his actions start to prove effective?"
Mr Salmond said measures already taken, including the emergency care action plan and more staff, had been welcomed by the health profession.
He vowed: "Working together we're going to bring about the sort of improvement that Scotland requires and the patients of Scotland deserve."
Ms Lamont claimed the A&E figures from 2012-13 were the "worst-ever statistics".
But the First Minister said the situation had been worse under the last Labour-led Scottish Executive, which Ms Lamont had been a minister in.
He told her: "The statistics for 2012-13 are there were 103,782 people waiting more than four hours, that is exactly the situation we are trying to tackle. That is out of a total attendances at A&E of 1,618,610.
"We're seeking to tackle these figures and bring them down to what we believe is a more acceptable level.
"But she said these were the worst figures ever. Let me give her the figures for 2006-07 when Johann Lamont was a minister.
"There 1,342,737 attendances, some 300,000 less than 2012-13. The number of people waiting more than four hours was 125,753."
The SNP leader continued: "Now that Johann Lamont has heard these figures, will she withdraw the suggestion that the 2012-13 year was the worst ever, since clearly it wasn't?
"Will she acknowledge that while we are trying to improve the performance it is substantially better than when she was a minister?"
While the target is for 98% of people attending A&E to be seen within four hours, the Scottish Government introduced an interim target of 95%.
Ms Lamont said the Audit Scotland report revealed that the Scottish Government plans to review the 95% interim target after September this year.
She told Mr Salmond: "We're not prepared to wait for his referendum before we make sure that the ill and injured don't have to wait for treatment."
She challenged the SNP leader on the issue at First Minister's Questions in the Scottish Parliament.
"The reality is the First Minister does not seem to understand or actually care about the problem," Ms Lamont said.
"We have a social care crisis which is fuelling an A&E crisis. People attending A&E need a bed but they can't get one because patients are being parked in inappropriate wards, waiting to be discharged but with nowhere to go."
Ms Lamont continued: "Hardworking nurses and doctors are not to blame, they are doing their best.
"Is the First Minister going to get serious about this crisis or is he just going to fiddle with the target again?"
Mr Salmond told her: "We're reviewing the 95% figure toward the end of the year because we want to drive it upwards towards the 98%."
He defended his party's record on the NHS, saying: "This government, unlike the Labour government, has pledged to protect real spending in the National Health Service and we have done so.
"Last December the figure increased to 93% of patients who were being seen in four hours, we want to get that figure higher, to the interim target of 95% then on to 98%."
But he said Ms Lamont "should recall that she was a minister and Andy Kerr was health minister in quite recent history the figure was 87.5%.
"That figure was hailed by Andy Kerr as showing the vast majority of A&E departments were meeting the four-hour target".
Mr Salmond insisted his Government's investment in the NHS was "paying off", telling MSPs: "There is an improvement, an improvement that we intend to drive up further thanks to the investment plans."
But in contrast he claimed Ms Lamont and Labour were "fundamentally lacking in any credibility on the National Health Service".