The chairman of the U.S. Civil Service Commission issued a statement yesterday deploring "intemperate attacks' on President Carter by the American Federation of Government Employees (AFGE).

The official, Alan Campbell, said the administration had been "clear and frank from the beginning" in telling unions what it would support.

Delegates to the AFGE convention in Chicago decided Monday to withdraw the union's support for Carter's proposals to overhaul the civil service system, claiming the president had lied to them.

Campbell said he does not expect the AFGE action to have a major effect on consideration of the civil service bill in the House and Senate.

On the contrary, he said, union leaders who urge their members to spurn the program "run a real risk that Congress will delete the labor provisions entirely" from the bill.

Campbell said the legislation gives organized labor several changes it has long fought for, such as arbitration rights in cases of firing and demotion and an independent authority to ensure fair dealings between the government and the unions - and it puts into statute the whole basis for federal labor relations.

But he said the administration will continue to oppose mandatory union dues, bargaining for wages, the right to strike and other changes sought by some union forces.

AFGE president Kenneth Blaylock, up for reelection at the convention, has stirred dissension in the ranks - and provided ammunition to his opponents - by supporting the Carter bill in exchange for concessions to the unions.