Opposite words for motivation:
counterincentive, disincentive.
Usage samples:
  1. At any rate, motivation is desirable for the dramatic confrontation, and time- the working- out- is an essential condition of motivation.
    "The Psychology of Beauty", Ethel D. Puffer.
  2. Without understanding his own motivation- and without caring- Max Hunter leaped into the sill of the terminal window.
    "The Cartels Jungle", Irving E. Cox, Jr..
  3. This suggests another test of good motivation.
    "Dramatic Technique", George Pierce Baker.
  4. But motivation does not mean sugar- coating.
    "Craftsmanship in Teaching", William Chandler Bagley.