A Chief Minister's Department spokesman said based on verification with the State Palace, Astana Negeri, the message was found to be false.
"The information is not true, I have already checked with Astana officers, no such was meeting held," he said when contacted.
The message made its rounds in the wake of the death of Sarawak Chief Minister Tan Sri Adenan Satem on Wednesday.
Meanwhile, the Sarawak Yang Dipertua Negeri's Office, in a statement, also denied that such an appointment had been made.
"The Sarawak Yang Dipertua Negeri's Office (Astana Negeri) denies appointing any Astana Negeri official to issue any statement pertaining to appointment of an acting Chief Minister or the funeral procession for Sarawak Chief Minister (Tan Sri) Adenan (Satem)," said the statement.
"The message on social media is the work of irresponsible parties who used the name of Astana Negeri to lend credibility.
"For the information of the public, Astana Negeri is an entity that is not involved in the state administration or Sarawak politics," it added.