Five Jordanians and six Uruguayans were on the aircraft as part of the surveillance mission named Minustah.
Michele Montas, a UN spokesperson in New York, said that the aircraft "was on a regular reconnaissance flight".
Rescue teams were sent to the area on foot because there are no roads in the area, but the UN said later that there had been no survivors.
"The cause of the crash is unknown but an investigation has begun," Vannina Maestracci, a UN spokeswoman, said.
A 9,000-strong UN peacekeeping force has been in Haiti since Jean-Bertrand Aristide, the former president, was ousted amid violence in 2004.