The pledge came on the eve of an official ceremony at which six 18th-century paintings will be returned to the descendants of Vienna-based industrialist Richard Neumann and another 17th-century work handed over to the family of Josef Wiener, a Prague banker who perished in the holocaust.
An estimated 2,000 works of art are currently held in trust by France's state museums pending identification of their owners.
Culture Minister Aurelie Filippetti said France would be taking a more active approach to identifying the rightful owners.
"Until now we have waited for inheritors or relatives to trigger research procedures," Filippetti said. "I want to introduce a more proactive approach under which France will seek the owners whether or not a formal request has been made."
American Thomas Selldorff will on Tuesday reclaim six German and Italian paintings that his grandfather, Neumann, was forced to sell in 1941 to raise the funds he needed to secure safe passage to Spain and then Cuba from Paris, where he had fled to from Vienna.
The paintings ended up in the hands of the Nazis, who had planned to transfer them to a museum that Adolf Hitler envisaged opening in his home town of Linz. After the end of the war, they were placed in museums around France, three of them in the Louvre.
The seventh painting that will be handed over on Tuesday is a work, "The Stop" by Dutch painter Pieter-Jansz van Asch (1603-1678) which was confiscated by the Nazis from Wiener.
At the end of the war, the victorious allied powers generally sent paintings back to their countries of origin: the van Asch work was sent to France, rather than the Netherlands, by mistake.