The women were arrested Thursday in connection with gas cylinders found inside a car left in front of Notre Dame Cathedral in Paris. One of the women had a letter in her purse swearing allegiance to ISIS, Molins said.
In the letter, she said she was answering the call of Abu Mohammad al-Adnani, according to Molins. Adnani, one of the highest-ranking figures in ISIS, was killed in late August.
The letter also said that "I am attacking you in your lands in order to terrorize you," according to Molins.
The prosecutor said one of the terror cell members, identified as Sarah H., was supposed to marry Larossi Abballa, the man who killed two police officers in Magnanville, France, in June.
After police shot Abballa, she then was supposed to marry Adel Kermiche, who killed a priest in Saint-Etienne-du-Rouvray, France, in July. Kermiche was also killed.
Describing the women as radicalized, the three were likely planning an "imminent and violent" attack, French Interior Minister Bernard Cazeneuve said Thursday after their arrests near Paris.
A police officer was injured in the shoulder when one woman attacked him with a knife in Boussy-Saint-Antoine, southeast of Paris, Cazeneuve told reporters. The injury was not life-threatening.
"I would like to express my gratitude to him and to his colleagues who had to open fire when faced with individuals armed with knives," the minister said.
One of the women also was hurt.
The minister said the women are 19, 23 and 39. CNN affiliate BFMTV said the owner of the car reported two daughters as missing and they were arrested Thursday. It said the 19-year-old woman stabbed the officer and was injured.
French President Francois Hollande said Friday that authorities had information enabling them to foil the attack and thanked the security services for capturing the suspects.
BFMTV said a car with a half-dozen gas cylinders was found Sunday near Notre Dame. One cylinder was empty, and the others were reportedly full. No detonator or firing device were found, and the vehicle was not reported as stolen.
France has been under a state of emergency since the Paris terror attacks in November, and authorities have struggled to monitor thousands of domestic radicals on their radar.
One of the two suspects in the priest's killing in northern France was known to anti-terror authorities after attempting a trip to Syria, a French anti-terrorism prosecutor said.
The priest's killing followed a string of violent attacks across Europe, some claimed by ISIS, including the Bastille Day attack in Nice.