David Cameron said former Tory chief whip Andrew Mitchell was owed an apology as the row between police and politicians over the "plebgate" affair escalated.
The Independent Police Complaints Commission (IPCC) said Inspector Ken MacKaill, Detective Sergeant Stuart Hinton and Sergeant Chris Jones should have faced misconduct hearings for lying about what Mr Mitchell said in a private meeting about the row last year.
At Prime Minister's questions Mr Cameron said the conduct of the officers, who were representing the Police Federation, was "not acceptable".
He said Mr Mitchell was "owed an apology, the conduct of these officers was not acceptable" and "these things should be properly investigated".
The Prime Minister backed the stance taken by Home Secretary Theresa May, who has insisted West Mercia Police force was "quite wrong" not to take disciplinary action.
The force's chief constable, David Shaw, has been summoned to give evidence to the Home Affairs Select Committee on the issue next week .