Deputy Neil Inder has been found in breach of Guernsey's Code of Conduct for States Members.
He was challenged for publicly criticising Deputy Dawn Tindall as well as civil servants in a radio interview last month.
Deputy Tindall lodged a complaint against him, claiming he referred to her as someone with a "tissue thin ego" and as "an empty chair".
Deputy Inder said he "was not specifically referring to Deputy Tindall" when he made the comments.
An investigation panel found Deputy Inder breached the Code by publicly criticising civil servants and not giving them an opportunity to defend themselves.
However, they found he did not breach the code when referring to Deputy Tindall.
The panel concluded the breach was "minor" but have formally cautioned Deputy Inder.