"We say to Qaddafi that we will not ease our pressure and to his opponents that we will not abandon them," French Defence Minister Gerard Longuet was quoted as saying by the newspaper Le Journal du Dimanche.
"Things have to move more in Tripoli... the population must rise up," he added.
With their bombing campaign dragging on unresolved, France and Britain have been forced to accept that Kadhafi may stay in Libya if he quits power under a ceasefire, despite calls for international justice.
"We are signed up for the duration and are thereby facilitating a negotiated settlement" between Qaddafi's regime and the rebels backed by France and Britain, Longuet said in the interview published Sunday.
France last week was the first to openly suggest Qaddafi could stay under a negotiated settlement. Britain denied the joint position was a climb-down after it had repeatedly called for him to quit the country.
"France and Britain are not alone" in the NATO-coordinated campaign, "but it is true France would like its European Union partners – Spain, Germany, Poland and northern European nations – to get more involved alongside it," Longuet said.
"The more of us there are showing that nothing can happen with Kadhafi in power, the more we will manage to isolate him totally, and the quicker this war will end."