Several photographs posted on Twitter showed a long line of tourists waiting to board a return ferry to Manhattan.
"There was an evacuation of the island, following a report of a suspect package," a spokesman for the park police said.
New York police said the island was cleared of visitors by afternoon and a special team of explosives experts was sent to the island.
Authorities ordered the evacuation of the island in New York harbours after receiving a telephone call warning of a bomb, according to NBC television.
It said a police dog then picked up a suspicious scent in a locker area where visitors can leave their things.
"Please cooperate ladies and gentlemen and step quickly through the gap (in the barricades) to the rear of the vessel," visitors were told over the loudspeakers in a video recorded by a visitor.
"There is more seating available up top, so please do not stop or hesitate on the gangway."
Emergency personnel were dispatched to the site.
Thousands of people each day visit the Statue of Liberty, a colossal, 151-foot sculpture of a woman bearing aloft a torch.
A gift of France to the people of the United States, it was dedicated in 1886.