Presidential National Security Affairs Adviser Zbigniew Brzezinski publicly urged Western Europe and Japan yesterday to take more "tangible actions" against the Soviet Union in the wake of the invasion of Afghanistan, saying that a policy of "rhetorical unity and substantive passivity" is not acceptable.

Brzezinski's remarks, in a new conference at the National Press Club, were an unusually strong official statement of concern about the reactions of major U.S. allies to the Soviet invasion. Until now, Washington has been alternating between generalized appeals for support and expressions of satisfaction.

Brzezinski did not say what specific steps the allies should take against the Russians, but the proposed boycott of the Summer Olympic Games in Moscow and a tightening of East-West economic policy are among those most discussed in official circles.

In the economic field, the United States has urged allied nations to stop exports credits and other forms of subsidy to the Soviet Union, but so far there has been no agreement on this. The United States has also asked for allied help in shoring up Pakistan, Turkey and other economically stricken countries in strategic areas.

Brzezinski said that the Soviet challenge to the Persian Gulf affects European and Japanese interests more directly than those of the United States. "It behooves them to respond to that challenge not only rhetorically but tangibly. . . . Alliance solidarity requires it, the collective security of the West calls for it."

Brzezinski gave little encouragement to European suggestions that the Soviets be offered a "neutralized" Afghanistan as an inducement for withdrawall of their forces. While the United States is willing to explore them, such arrangements "can't be constructed on piles of corpses [or] massive suppression of a small nation of people who wish to assert their national and religious identity," he said.

The White House official charged that Soviet policy on Afghanistan is one of "fighting and talking" -- fighting to take over the country while talking "to divert public opinion, to dilute the condemnation of the Third World and the advanced world."

In other remarks, Brzezinski said:

The United States still hopes to pursue solution of the hostage crisis with Iran by peaceful means but "clearly maintains under international law the right to take recourse to alternative actions if the peaceful role does not succeed." This was a return to indirect suggestions of military action which the administration avoided during the hostage negotiations involving the United States commission.

Policy decisions involving high officials will be put in writing more often -- rather than being made by oral exchanges -- in order to prevent mistakes such as the recent turnabout on voting at the United Nations.

"It suits us just fine" if Pakistan decides to look to Islamic countries for its "first line of support" while obtaining economic aid from the United States. On Capital Hill, Deputy Secretary of State Christopher said he believes there is an opportunity for an economic aid relationship with Pakistan even if military aid does not develop.

Any indication of greater North Korean independence from the policy position of the Soviet Union is a "positive development" of which the United States aproves and a contribution to serious discussions between North and South Korea on a long-term basis. Brzezinski evidently was referring to North Korea's failure to endorse the Soviet action in Afghanistan.

Brzezinski told a luncheon meeting with a group of reporters, according to The Associated Press, that he favors Deputy Secretary of State Christopher to succed Cyrus R. Vance in the top U.S. diplomatic job in a second Carter administration. Brzezinski, often mentioned as Vance's successor as secretary of state, was quoted as saying, "who the hell wants that job" and the he prefers the variety and presidential access of his current post. Brzezinski was quoted as saying Carter is receptive to naming Christopher.