kill the messenger

(idiomatic) To blame a problem on whoever reported it; to hold somebody accountable a problem because he/she brought attention to it.

Example:   I know you won't like this news, but please don't kill the messenger.
1893 December 12, Rev. B. Minard, “Sunday in the Churches”, Lewiston Evening Journal, Maine:
  To disbelieve the message and seek to kill the messenger will not destroy the message