Officials for the airline and the Federal Aviation Administration said Flight 64 landed safely at 7:15 p.m. EDT at an airport in Halifax, Canada, after the pilot declared an emergency due to smoke in the mid-cabin.
The plane had departed from John F. Kennedy International Airport in New York at 5:55 p.m. EDT bound for Zurich.
American Airlines spokeswoman Mary Frances Fagan said there were 194 passengers and 12 crew members aboard.
Halifax Stanfield International Airport spokesman Peter Spurway said the smoke was traced to a fan motor in the bathroom.
All passengers got off safely, but one was taken away by ambulance to hospital, Spurway said.
"I don't know the nature of the issue whether it was related or not or whether it was just stress," Spurway said. "Everybody else is fine."
American was sending another 767-300 to Halifax on Tuesday night to pick up the passengers and take them on to Zurich, Fagan said, adding that the passengers likely would arrive in the Swiss city about eight hours late.