Lawyer Rafik Chekkat, founder of the Islamophobia platform, said Maarifi was arrested in the morning at her home and taken into custody.
He criticized the arrest and said it took place at a time when French soldiers who fought in Gaza "enjoy total impunity."
Comment: They're also over in Ukraine fighting alongside the Kiev-juntas Nazis, who are engaged in terrorist attacks and the torture of POWs: Russia releases names of French mercenaries in Ukraine, includes son of a General of France's Armed Forces
Thomas Portes, a lawmaker from the La France Insoumise, or France Unbowed (LFI) party, wrote that Maarifi has been released from custody.
"The search of the home in front of the family leaves no doubt about the desire to intimidate the voices that are raised to support the Palestinian people and demand an immediate ceasefire," he wrote on X.
Comment: Footage of Maarifi after being released:
Maarifi attended pro-Palestinian rallies in France to share her testimony about the crippling situation in Gaza.
She has also expressed her demand for an immediate cease-fire in Gaza and a boycott of companies supporting Israel.
Maarifi, who is known as one of the first French nationals to enter Gaza since Oct. 7, spent 15 days at the European hospital in Khan Younis.
Israel has continued a brutal offensive on Gaza since an Oct. 7 Hamas attack despite a UN Security Council resolution demanding an immediate cease-fire.
More than 40,800 Palestinians, mostly women and children, have since been killed and nearly 94,300 injured, according to local health authorities.
An ongoing blockade of the enclave has led to severe shortages of food, clean water and medicine, leaving much of the region in ruins.
Israel faces accusations of genocide for its actions in Gaza at the International Court of Justice.
This could be a far bigger operation than anyone ever thought. I always figured at least a small presence of US troops being permanently stationed there, but France? Israel has dirt on everyone, so it really wouldn't be much of a stretch to say there could be as many as 12 countries troops being there that have large enough militaries. How many of them are actively fighting in Gaza?
It looks like the ICJ needs to expand it's genocide investigation.