"No civilian need justifies the enrichment activities undertaken by Iran," Douste-Blazy told RTL radio.
"There is no trust today between Iran and the international community, because of doubts about the nature of Iran’s nuclear propramme," he said.
He said France "recognises more than ever Iran’s right to electro-nuclear energy, but to civilian and peaceful ends".
Iran announced this week that its scientists had successfully enriched uranium to make nuclear fuel, a process which can be extended to make the fissile core of a nuclear warhead.
Asked whether France believed Tehran was secretly developing nuclear weapons, Douste-Blazy said the International Atomic Energy Agency had "stressed a number of elements that it said could have a military nuclear dimension".
The Islamic republic insists its programme is peaceful, but the UN Security Council has set April 28 as a deadline for it to halt enrichment.
If Tehran continues to refuse to suspend its enrichment work, Douste-Blazy said the Security Council would be forced to take the "necessary measures", which could include possible sanctions.
Douste-Blazy stressed that France remained in favour of a negotiated settlement to the dispute, saying that military action against Iran was "absolutely not on the cards".
"We are on the Security Council, we have always believed in multilateralism, we believe in the United Nations, it is within that framework that we must discuss this," said Douste-Blazy.
Officials from permanent Security Council members Britain, France and Russia, and Germany, all said this week that Iran had taken a "step in the wrong direction"
cr/ec/ss