When they refer to themselves, they describe themselves as 'Autonomous Robotic Organisms' from the planet Cybertron. Not 'robots'. Optimus Prime himself said, "You can call us 'Autobots' for short." They also use the term 'Autobots' when referring to each other generically or as a group. There you have it from the head Autobot himself.
http://www.youtube.com/watch?v=iXuKUy-J4qM