Playing in their fourth finals, the north Africans were bitterly disappointed not to progress beyond the opening round for the first time in a group many considered one of the easiest in the competition.
In their opening two matches the Tunisians took the lead against both Saudi Arabia (2-2) and Spain (3-1), only to emerge with a draw and a defeat, and they then failed to mount a real challenge to Ukraine in a match they had to win.
"I don't know whether we have progressed or regressed, that's the big question mark," a subdued and philosophical Lemerre said at a news conference.
"I think we must work tremendously on the building and pre-building of players in order that we can have young players reaching international tournaments," he added.
NEW STANDARD
Tunisia set a new standard for their continent's football at their debut World Cup in Argentina in 1978, a shock 3-1
In the 11 games they have played since then, the 2004 African Nations Cup champions have failed to add to their victory tally.
Defender Anis Ayari noted that Tunisia had only just missed out on making it through to the next round this time despite a lack of experience in the squad.
"This was the first World Cup for certain players and we haven't been that far from qualifying," Ayari told reporters. "The players have to work extra hard because the World Cup is another world in football terms."
Lemerre, who turned 65 on June 18, said it was time for the Tunisian players and coaching staff to pick themselves up and look to the future, despite the disappointment felt at their early elimination.
"We certainly share the disillusionment of the Tunisian fans but life goes on and we now have to think about qualification for the next African Nations Cup as well as the next World Cup."
(Additional reporting by Sonia Oxley)