French President Emmanuel Macron blamed the EU's slow Covid-19 inoculation campaign on a lack of ambition and a failure to appreciate how quickly a vaccine could be developed last year.
"Everybody, all the experts said: 'Never in the history of mankind was a vaccine developed in less than a year'," Mr Macron told Greek television channel ERT.
"We didn't shoot for the stars. That should be a lesson for all of us. We were wrong to lack ambition, to lack the madness, I would say, to say: 'It's possible, let's do it'," he said.
The EU is responsible for procuring and distributing vaccines to member states, but lags well behind comparable countries such as Israel, the UAE, the UK and the US in the number of shots per capita administered.
"We didn't think it would happen that quickly … you can give that to the Americans, as early as the summer of 2020 they said: 'Let's pull out all the stops and do it'," Mr Macron said.
"As far as we're concerned, we didn't go fast enough, strong enough on this. We thought the vaccines would take time to take off."
France, where about 6.6 million people have been given at least one shot, has struggled with domestic issues including trying to a convince large chunks of the population that are sceptical about vaccines.
The EU, which is furious with drug maker AstraZeneca over missed delivery targets, on Wednesday tightened controls on vaccine exports in an effort to speed up its campaign.
It came amid a surge in virus cases on the continent that has forced many EU member states to tighten restrictions.
German Chancellor Angela Merkel blamed supply problems on a lack of production capacity.
"British production sites are manufacturing for Britain and the United States is not exporting, so we are reliant on what we can make in Europe," she told Germany's parliament on Wednesday.
"We have to assume that the virus, with its mutations, may be occupying us for a long time to come, so the question goes far beyond this year."
She also defended the decision to jointly procure vaccines with EU member states.
"Now that we see even small differences in the distribution of vaccines cause big discussions, I would not like to imagine if some member states had vaccines and others did not," Ms Merkel said.
"That would shake the internal market to its core."