Interior minister Bernard Cazeneuve said suspect had 'key role' in recruiting French youths in Strasbourg and Toulouse and sending them to Syria.
Meriam Rhaiem, 25, made headlines earlier this year with an emotional appeal to recognise her baby girl, aged 2, as 'the youngest French hostage'.
The pair, aged 15 and 17, were arrested on suspicion of helping a 14 year-old girl travel to Syria to join jihadist forces.
Suspect arrested by security services on arrival in France as part of preliminary investigation into possible 'conspiracy to plan terrorist acts'.
Targets revealed in online messages between a 29-year-old French citizen and a 'senior member' of al-Qaeda offshoot group.
Gilles Le Guen, also known as Abdel Jelil, arrived in Paris on Tuesday after being captured by French forces in the Malian city of Timbuktu.
Authorities had been searching for Gilles Le Guen since October when he published a video in which he warned France not to interfere in Mali.