The Reagan administration yesterday retreated from its short-lived effort to police contacts between officials and reporters, but instituted a new system designed to make it easier to identify officials who leak national security information to the news media.

A directive signed by President Reagan orders that all officials who read classified documents prepared by or intended primarily for the National Security Council must sign an attached cover sheet. If such information were to leak, investigators presumably would target their search for the leaker on people whose signatures appeared on the sheet.

By signing the cover sheet an official acknowledges that he understands the laws governing classified information and promises to cooperate with any "lawful investigation by the United States government" of any unauthorized disclosure.

White House communications director David R. Gergen said the procedure is designed to restrict access to national security information to a minimum number of people.

The directive is the result of a review by White House national security affairs adviser William P. Clark that began early last month after Reagan complained at a Cabinet meeting about leaks of memoranda and policy decisions.

It reflects some second thoughts by Clark, who issued a more sweeping directive Jan. 12 that required the advance approval by "a senior official" of all contacts between reporters and officials "in which classified National Security Council matters or classified intelligence information are discussed."

That provision prompted criticism from reporters and some government officials who said it would chill a wide range of useful contacts.

Clark met Monday with four reporters, at his request, to discuss a draft directive that still contained the prior-approval condition and a requirement that officials write a memo to the approving official reporting on the contact with the reporter.

Clark decided overnight to drop those requirements. One official said Reagan had indicated that he does not want to get into "an us guys vs. you guys situation."

Gergen said the entire review of the situation and the differing directives have "sent a message through the ranks that the president regards disclosure of National Security Council information as a serious matter."

Although the directive applies only to National Security Council material, the administration expects the CIA and other agencies and departments to draft new procedures for handling sensitive information.

The administration's concern about security centered on two leaks: a Washington Post article reporting that crates containing Soviet aircraft had been spotted in Cuba in a possible violation of the 1962 U.S.-Soviet agreement that prohibits the introduction of offensive weaponry into Cuba, and the leak of details of Reagan's decision on what type of fighter planes to sell Taiwan.

All administrations have been troubled by leaks at one time or another and have sought ways to plug them. The most vigorous and ill-fated of the attempts was the Nixon administration's "plumbers" operation.

Gergen said the new directive represents "a determined effort" to "draw a proper balance between the public's right to know and the government's need to protect classified information."

Attorney General William French Smith has been asked to form an interagency group by March 1 to look into the effectiveness of the laws prohibiting unauthorized disclosure of classified information. Gergen said the group also will study the penalties for such disclosure, but that no new penalties are envisioned.

The cover sheet will be attached to a document at the time the document is submitted to an assistant secretary or an official of equivalent rank. After it is attached it must be signed by all officials no matter what their rank, Gergen said.

The sheet will carry this notice:

"The attached document contains sensitive National Security Council information. It is to be read and discussed only by persons authorized under the law.

"Your signature acknowledges you are such a person and you promise you will show or discuss information contained in the document only with persons who are authorized by law to have access to this document.

"Persons handling this document acknowledge he or she knows and understands the security law relating thereto and will cooperate fully with any lawful investigation by the United States Government into any unauthorized disclosure of classified information contained herein."