Spokesman Eric Fehrnstrom said Romney and his wife were on an Air Canada flight to Los Angeles on Monday when Romney asked the passenger sitting in front of his wife, Ann, to raise his seat back before take off.
Fehrnstrom said the passenger became enraged and took a swing at Romney.
"The passenger became physically violent," Fehrnstrom said. He said the former Massachusetts governor did not retaliate, letting the airline crew respond. Romney was unhurt.
The plane returned to the gate, the passenger was removed and the flight took off a short time later.
The Romneys had been in British Columbia since Friday to watch the opening of the Olympic Winter Games.
- AP, with Bloomberg News