The car was impounded and was being searched, two law enforcement officials told CNN.
There was no immediate indication that there was an explosive device in the car.
The threat caused authorities to set up a security perimeter around the White House.
Several streets around the White House have been closed.
Investigators were questioning the suspect to determine what possible motive he could have had and whether he was acting alone.
President Donald Trump was not at the White House at the time of the security compromise.
The incident happened more than a week after a man scaled an outer perimeter fence of the White House then climbed over a vehicle gate and another fence to get near the East Wing.
Authorities acknowledged on Friday that the intruder, identified as Jonathan Tran, was on the grounds for more than 15 minutes prior to his arrest.