"I demand these journalists be freed immediately," Hollande said during a visit to Japan.
The Wall Street Journal reported Friday the journalists, identified as Didier Francois and Edouard Elias, hadn't been heard from for 24 hours.
Hollande said French authorities did not know any details surrounding their disappearance.
At least 40 journalists have been killed and 21 others have been kidnapped in Syria since the start of peaceful protests in 2011 that devolved into civil war, the Committee to Protect Journalists, a non-profit group based in New York, said.
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Syrian Al Qaida group executes Lebanese soldier