The 37-year-old New Jersey man allegedly pulled up in a minivan outside the landmark in Manhattan on Wednesday night, walked around the area, and then returned to the vehicle to retrieve the items, said New York Police Department (NYPD).
“As he enters the cathedral he’s confronted by a cathedral security officer who asks him where he’s going and informs him he can’t proceed into the cathedral carrying these things,” said NYPD deputy commissioner of intelligence and counterterrorism John Miller.
“At that point some gasoline apparently spills out onto the floor as he’s turned around.”
Security then raised the alarm with counter-terrorism officers who were standing outside, Mr Miller said.
The officers caught up with the man and he was arrested after he was questioned and his story was found to be inconsistent.
“His basic story was he was cutting through the cathedral to get to Madison Avenue,” said Mr Miller.
“That his car had run out of gas. We took a look at the vehicle – it was not out of gas and at that point he was taken into custody.”
He added: “It’s hard to say exactly what his intentions were, but I think the totality of circumstances of an individual walking into an iconic location like St Patrick’s Cathedral carrying over four gallons of gasoline, two bottles of lighter fluid and lighters is something that we would have great concern over.”
Mr Miller said the suspect is known to police and officers are currently looking into his background.
St Patrick’s Cathedral was built in 1878 and has installed a sprinkler-like system during recent renovations. Its wooden roof is also coated with fire retardant.
It is not yet clear what caused the blaze, which took firefighters 15 hours to put out.
French president Emmanuel Macron vowed the 850-year-old Gothic landmark would be rebuilt within five years.
A combined €800m (£693m) has already been pledged by a number of companies and business tycoons to help rebuild the Unesco World Heritage site.