General:
* Unpleasant
* Unfavorable
* Offensive
* Repulsive
* Unwelcome
* Objectionable
* Aversive
More specific:
* Rude: If the disagreeable behavior is impolite.
* Unkind: If the disagreeable behavior is cruel or hurtful.
* Hostile: If the disagreeable behavior is aggressive or threatening.
* Irritating: If the disagreeable behavior is annoying or frustrating.
* Abhorrent: If the disagreeable behavior is deeply offensive or morally wrong.
* Disgusting: If the disagreeable behavior is repulsive or sickening.
* Crude: If the disagreeable behavior is coarse or vulgar.
* Unpalatable: If the disagreeable behavior is distasteful or unacceptable.
The best adjective to use will depend on the specific context and the reason why the behavior is considered disagreeable.