Jonathan Baume, general secretary of the First Division Association, said many government employees could now face "a huge fall" in their pensions because of the planned changes.
Mr Baume warned it was only a matter of time before the government looked to change pension arrangements for headteachers and senior managers in the NHS and local authorities.
"The government wants our members to accept what is likely to be an inferior pension and the proposals allow government a free hand to increase civil servants' contribution rates whenever they like.
"Those who lose most will be experienced, high performing managers who are responsible for driving the government's modernisation agenda.
"The government is unravelling the fabric of the moral contract between government and our members who have served the public with dedication, loyalty and professionalism."
Mr Baume said he understood that many private sector pension schemes had suffered in recent years, but he argued this was no reason for "equality of misery".
Asked on BBC Radio 4's Today programme about the prospect of industrial action, Mr Baume replied: "We have ruled nothing in or out."
The FDA, which represents 12,000 senior public servants said it was dismayed that the government had "tarted up" its proposals under the guise that they will improve mobility across the public sector.
The Public and Commercial Services Union has already warned of industrial action in protest at the increase in pensions age to 65 and replacing the final salary scheme with one based on career average wages.
Unions representing millions of public sector workers will meet next week to decide their response to "attacks" on pensions, with some officials calling for coordinated industrial action.
