Dic: Synonyms: interfere, meddle, tamper(1)

These verbs mean to intervene unasked in the affairs of others and often in an impudent or indiscreet manner.

• Interfere implies action that seriously hampers, hinders, or frustrates:
  .... "Romantics of all ages can recall occasions when lust interfered with reason" (Christine Gorman).
• Meddle stresses unwanted, unwarranted, or unnecessary intrusion:
  .... "wholly unacquainted with the world in which they are so fond of meddling" (Edmund Burke).
• To tamper is to interfere by making unsought, unwelcome, often destructive changes or by trying to influence another in an improper way:
  .... "a large number of persons accused of . . . tampering with ballot boxes" (James Bryce).

.... The American Heritage, http://www.thefreedictionary.com/interfere