The plane had "multiple flat tires upon landing," according to the airline.
The left landing gear of the Boeing 757 was stuck in a grassy area after Flight 627 from Denver landed at Newark at 1 p.m., the Federal Aviation Administration said.
United Airlines said some customers had minor injuries and that they refused medical attention.
Flights in and out of the airport were briefly suspended, the airport said, but had resumed with delays of close to two hours by 3 p.m.
The Chicago-based airline said it is evaluating the damage the aircraft suffered.
"Were in close touch with the FAA and airport authorities and are working expeditiously to safely remove the disabled aircraft so that operations at the airport can return to normal," it said in a statement.