unprovoked
1. [ adjective ] occurring without motivation or provocation
Synonyms: wanton motiveless
Examples:

"motiveless malignity" "unprovoked and dastardly attack"- F.D.Roosevelt

Related terms: unmotivated
Similar spelling:   unproved
  unprovoking
  unprovocative
  unprovable
  unprompted
  unpromised
  unproven
  unbroken
  unprotected
  unprocessed