President Hollande has put France on war footing and proposed expanded powers for security services for the next three months. This comes as two were killed and seven arrested in a raid on a suspected mastermind.
Paris prosecutor Francois Molins said telephone surveillance and witness statements had led police to believe that Belgian jihadist Abdelhamid Abaaoud was in an apartment in Saint-Denis in northern Paris.
Anti-terrorist police flooded the streets near the building, and soldiers were also deployed. The operation lasted around seven hours and left two people dead, including a woman who police say blew herself up.
But it's still unclear whether Abaaoud was among those killed or captured by French commandos.
"As things stand, it is impossible to give you the identities of the people detained, which are being verified," Molins said. "All will be done to determine who is who, and based on the work of forensic police, we'll tell you who was in the apartment - and what consequences it will have for the development of the investigation."
French President Francois Hollande praised the country's security services and said that France was "at war" with the Islamic State group, which has claimed responsibility for the coordinated attacks that killed at least 129 people.
"It is the entire country that's been attacked," Hollande told a gathering of French mayors. "For what it represents, the fight we are leading to eradicate terrorism. And simply for what we are."
In his televised remarks, Hollande urged the nation not to "give in to fear" or extremist sentiments.
"No anti-Semitic or anti-Muslim act can be tolerated," Hollande said.
Members of special French RAID forces in Saint-Denis, near Paris, France, on November 18, 2015. This week the French government will consider extending the 'state of emergency' police powers for an additional three months.
State of emergency for three months?
The president's remarks come the same day that a bill to extend France's state of emergency powers for three months is being considered by the cabinet.
Hollande had declared a state of emergency for 12 days following Friday night's deadly attacks, and parliament must approve extending it. If passed by the cabinet, it could move its way through both legislative houses by the end of the week.
The state of emergency increases search-and-arrest powers of the police and limits public gatherings, including those in mosques and other houses of worship.
This comes the same day as the European Commission considers a bloc-wide ban on certain semi-automatic firearms and standardized markings across the European Union.
"Organized criminals accessing and trading military-grade firearms in Europe cannot and will not be tolerated," European Commission President Jean-Claude Juncker said.
jar/jil (AP, AFP, dpa)