Congress, making good on earlier warnings, has ordered the Reagan administration to stop asking government workers to sign controversial secrecy pledges governing classified information.

The order, added as a rider to the fiscal 1988 spending bill signed into law Tuesday by President Reagan, bars any department from spending money to implement or enforce what are known as Standard Form 189 and Standard Form 4193.

The prohibition is good throughout fiscal 1988, which ends next Sept. 30, "and should force the administration to come up here and work something out with us if they want to continue using such pledges," a House staff official said.

Standard Form 189 has been used by some government agencies since 1985. Only within the last year, after the Defense Department began enforcing demands that it be signed, did its use become public knowledge and congressional committees begin investigating the matter.

Several congressional leaders, including Reps. John D. Dingell (D-Mich.) and Jack Brooks (D-Tex.) and Sen. Charles E. Grassley (R-Iowa), subsequently urged the administration to suspend use of that form.

The administration countered that the form was designed simply to underline federal workers' obligations to protect classified information.

Standard Form 189 asks workers to acknowledge the government's right to fire them or to prosecute them on criminal charges for releasing classified or "classifiable" information.

Congressional leaders have contended that SF 189 is so broadly worded that employes are being asked to sign away their rights.

Dingell, chairman of the House Energy and Commerce Committee, said the term "classifiable" in the form lets the government fire a worker for releasing information not formally classified at the time of release.

Grassley, who played a key role in adding the new prohibition to the spending bill, also maintained that the form amounts to a "broad gag order to silence whistle-blowers privy to potentially embarrassing information about waste in government."

SF 4193 is a separate, more restrictive pledge demanded of employes who are cleared to handle Sensitive Compartmented Information, the highest secrecy category. That form includes a "prepublication" agreement requiring workers to submit for a security review any book or article they write.

Both forms are being challenged in court by federal employe unions.

Under the new congressional prohibition, the administration cannot continue to ask employes to sign either form, nor can it enforce certain provisions of the forms for employes who already have signed.

In essence, the congressional language bans enforcement of provisions that rely on vague terms, such as "classifiable," that would interfere with disclosures to Congress and that would conflict in any way with a federal law that shields whistle-blowers who disclose wrongdoing.

The prohibition also makes clear that the administration cannot take disciplinary action against an employe who releases information because he or she never received proper prior notice that the document was classified.

House officials, who asked not to be named, said the congressional directive probably would not affect enforcement actions involving the SF 4193 prepublication pledge.

The Information Security Oversight Office, an obscure agency attached to the General Services Administration that developed the forms, ordered federal agencies this summer to temporarily stop revoking security clearances of employes who refused to sign. That move was prompted by legal challenges.