Secret Service spokesman Jim Mackin said a man jumped the southeast fence of the White House, near where the motorcade was waiting for the president.
He was immediately apprehended and taken into custody, Mackin said, adding that the fence jumper was not armed.
Two heavily armed Secret Service agents, including one with a large automatic weapon, were seen patrolling a bushy area near the White House sculpture garden shortly after the man was reported to have entered the White House complex.
All exits to the White House were briefly locked, Mackin said.
The incident did not affect the president's schedule. Clinton, who is notoriously late, had still not left for his evening event nearly an hour after the man jumped the fence, Mackin said.
Secret Service agents are interviewing the man, described only as a white male, and he probably will be charged Tuesday night, Mackin said.