Addressing Parliament on Tuesday, Valls said Rouhani had accepted an invitation extended by French Foreign Minister Laurent Fabius in July.
Fabius traveled to Tehran following the announcement of the nuclear deal between Iran and a group of world powers.
Valls said French President François Hollande will host Rouhani “because after the conclusion of an agreement on its nuclear program, Tehran must weigh in positively in favor of a political solution” in Syria, the AFP news agency reported.
Last week, France joined the U.S.-led campaign against ISIS in Syria after flying reconnaissance missions over the country, the Associated Press reported.
France will soon begin airstrikes in Syria and has already taken part in airstrikes against ISIS targets in Iraq.
France was also one of the six world powers—the U.K., U.S., France, China, Russia and Germany—that signed the nuclear deal with Iran earlier this year.