President Reagan, acting on the recommendation of a task force headed by Vice President Bush, soon will issue an executive order declaring terrorism "a potential threat to national security" and pledging to resist it "by all legal means available," senior administration officials said yesterday.

While the directive calls for greater international sharing of intelligence information and increased military contingency planning, it sidesteps the divisive issue in the administration on when it is appropriate to use military force against state-supported terrorism.

Secretary of State George P. Shultz, an outspoken advocate of a firmer antiterrorist policy, said this week that the United States "cannot wait for absolute certainty and clarity" before using force against terrorists or countries that support them. Defense Secretary Caspar W. Weinberger has repeatedly urged caution in using military force on the basis of circumstantial evidence and this week criticized those who seek "instant gratification from some kind of bombing attack without being too worried about the details."

Reagan's directive will endorse a task force report that is two inches thick and contains some 50 recommendations, the officials said. Many of the recommendations simply formally endorse current administration policy, such as not making concessions to terrorists and pledging to pursue and prosecute those involved in terrorist acts. The document also endorses some measures already taken by the administration, such as improving security at U.S. embassies and military installations overseas.

The report is intended to provide Reagan with a document that will stand as a comprehensive antiterrorist policy and refute critics who charge that the administration is indecisive or "lacks a policy" to combat terrorism, said an official familiar with its contents. But it does not resolve the basic issue of defining the circumstances under which the United States should use military force against nations, such as Libya, that the president has identified as sponsoring the Dec. 27 airport attacks in Rome and Vienna.

"The report does what circumstances are already doing -- it defines the differences in approaches to the problem," another official said. "Basically, it streamlines the process. But the question of when a military response is appropriate is left for further study."

While the official acknowledged that the recommendations were "not dazzling," he said that the report would serve the purpose of focusing the dispute in the administration so that "we'll bump up against the fundamental differences more quickly."

In addition to the long-running dispute between Shultz and Weinberger and their subordinates, administration policy toward terrorism has been plagued by difficulties in coordinating the actions of competing agencies. One official familiar with the process said yesterday that it is sometimes difficult for the administration to respond in a timely fashion even when there is not disagreement "because you have to sort through too many details and people, some of whom are not particularly well-versed in what has to be done."

Bush, who has been involved in antiterrorist planning since he was director of central intelligence for President Gerald R. Ford, was described as hoping that the delineation of agency responsibility provided by the report would help produce more rapid decisions in dealing with terrorist acts.

The report, which will have the force of executive order after the president issues his directive, says that the State Department is the lead agency for dealing with international terrorism and that the Defense Department is the action arm for operations in the international arena. But the national security affairs office in the White House, headed by John M. Poindexter, is given responsibility for implementing the recommendations. These definitions give what one official described as "a delicate push" toward greater control of antiterrorist policy by the White House without withdrawing authority from the Pentagon or State Department.

The task force was appointed by Reagan last June 20 while American passengers on TWA Flight 847 were being held hostage in Beirut and the day after a terrorist attack on a restaurant in El Salvador killed 15 persons, including four U.S. Marines. The 15-person panel presented its report to Reagan Dec. 20, and an unclassified version is scheduled to be made public in mid-February.

The report also includes a section on public attitudes toward terrorism based on a poll commissioned by the task force.

Officials denied several published accounts that they said went beyond the actual conclusions of the task force. In particular, they objected to reports that the task force recommended an international antiterrorist force, saying that it instead urges more "multinational cooperation," primarily through intelligence sharing.

White House spokesman Larry Speakes also denied a report that Reagan, acting on the recommendation of the task force, would ask Congress for a resolution empowering the executive branch to use "whatever force is required" to deal with terrorism.