Seven people were injured when an East River Ferry boat slammed into a dock near the South Street Seaport on Wednesday.

The vessel was pulling in at Pier 11 on at around 5:40 p.m. when it struck the mooring, knocking passengers to the deck.

Passenger James Manning said it appeared the operator couldn’t reverse thrust because one of his engines had cut out.

“So he just slammed very hard into the front of the pier,” said Manning, 45.

“Everybody was standing in the front, ready to disembark, so everyone just kind of fell over,” he went on. “Quite a few little kids went flying. Another guy fell out of wheelchair.”

Two people were taken to a local hospital, while the other five declined medical attention, officials said.

An East River Ferry spokesman blamed choppy waters for the mishap.