"It's the street where Charlie Hebdo used to be, this is the way the Islamist terrorists operate," Darmanin told broadcaster France 2, referring to the satirical weekly stormed in 2015 by extremist gunmen. "This is a new bloody attack on our country."
Seven people including the main suspect are being held for questioning in connection with the attack.
A man armed with a meat cleaver wounded two in Paris Friday outside the former offices of satirical weekly Charlie Hebdo before being arrested by police, three weeks into the trial of suspected accomplices in the 2015 massacre of the newspaper's staff.
France's PNAT specialist anti-terror prosecution office said it has opened a probe into charges of "attempted murder related to a terrorist enterprise" as well as "conspiracy with terrorists".
Charlie Hebdo has angered many Muslims around the world by publishing cartoons of the Prophet Mohammed over the years, and in a defiant gesture reprinted some of the caricatures ahead of the trial.
Twelve people, including some of France's most celebrated cartoonists, were killed in the attack on Charlie Hebdo by Islamist gunmen on January 7, 2015.
Paris police said two people were "critically wounded" in Friday's attack near the paper's former offices in the French capital's 11th district. The magazine's new address is kept secret.
Prime Minister Jean Castex, visiting the scene, said the lives of the two victims "are not in danger, thank God".
The Premieres Lignes news production agency said the wounded were its employees - a man and a woman taking a cigarette break outside.
"They were both very badly wounded," the founder and co-head of Premieres Lignes, Paul Moreira, told AFP.
Another employee, who asked not to be named, said he heard screams.
"I went to the window and saw a colleague, bloodied, being chased by a man with a machete."
The company specialises in investigative reports and produces the prize-winning Cash Investigation programme.
Paris prosecutors said the "main perpetrator" was arrested not far from the scene of the crime.
According to PNAT head Jean-Francois Ricard, the suspect was an 18-year-old man. Initial indications are that he was born in Pakistan.
Child welfare authorities said the suspect had shown "no sign of radicalisation" while under their care after arriving in France in August 2018 and claiming to be a minor.
The suspect was arrested in June for possession of a stabbing weapon, a source close to the case said.
A second person, a 33-year-old Algerian, was arrested later for questioning to determine possible links to the "main perpetrator", Ricard said.
Five more people - all men born between 1983 and 1996 who were arrested in the Paris suburb of Pantin during a search of a property linked to the main suspect - were also being held for questioning, a judicial source said late Friday.
Five schools in the area went into lockdown for several hours after the attack, and half a dozen nearby metro stations were closed.
"Around noon we went for a lunch break at the restaurant. As we arrived, the manager started shouting 'Go, go there is an attack...' We ran to lock ourselves in our shop with four customers," Hassani Erwan, a 23-year-old barber, told AFP.
In a Twitter post, Charlie Hebdo expressed its support for "the people affected by this odious attack".
They were victims of "fanaticism" and "intolerance", Charlie Hebdo said, calling the main suspect and his possible accomplice "terrorists".
'Underestimated the threat'
The stabbing came during the trial of 14 alleged accomplices of brothers Said and Cherif Kouachi, the perpetrators of the 2015 attack on Charlie Hebdo that was claimed by a branch of Al-Qaeda.
A female police officer was killed a day later, followed the next day by the killing of four men in a hostage-taking at a Jewish supermarket by gunman Amedy Coulibaly.
The trial has reopened one of the most painful chapters in France's modern history, with harrowing testimony from survivors and relatives of those who died.
The magazine received fresh threats from Al-Qaeda this month after it republished the controversial cartoons.
More than 100 French news outlets on Wednesday called for continuing support for Charlie Hebdo against what they described as the "enemies of freedom".
Just this week, police relocated the paper's head of human resources, Marika Bret, from her home following death threats.
Darmanin said he had asked the Paris police chief "why we we underestimated the threat" in the street next to Charlie Hebdo's former offices.
The co-head of Premieres Lignes, Luc Hermann, told BFMTV that since the start of the trial "there has been absolutely no security for this street and symbolic building".