The Soviet Union today assailed President Carter's new nuclear strategy as an act of "insanity" conceived by persons "who have lost all touch with reality and are prepared to push the world" into nuclear war.

The vitriolic attack by the official news agency Tass came after somewhat more restrained expressions of concern over the so-called presidential directive number 59, details of which surfaced in Washington last week.

The Tass commentary said that "mounting waves of war hysteria are sweeping the White House," and that "things are now far more serious because President Carter, as it is reported, sanctioned the new nuclear strategy." Tass said the essence of the strategy is "the threat of striking a first blow at military installations in the Soviet Union."

The strategy, as reported in Washington, involves gradually changing the U.S. nuclear arsenal's targets from Soviet cities and industrial centers. It would put greater emphasis on smaller scale attacks that would destroy Soviet military forces and command centers. The new strategy relies heavily on new, more accurate nuclear weapons, and would in theory make possible a nuclear exchange short of total war.

The strategy, evolved over the past three years inside the Carter administration, in effect replaces the strategy of Mutual Assured Destruction, or MAD, according to which any nuclear exchange would unleash a total retaliatory blow aimed at the destruction of some 200 Soviet cities.

Tass called the administration plan "an obvious and extremely dangerous playing with fire." Another Tass commentary said that as a result "the Soviet Union will have to draw the necessary conclusions."

One conclusion, Tass said, is that the concept of "limited nuclear war" Carter has advanced will inevitably lead to an accelerated arms buildup. "It would be naive to think that the Soviet Union will stand idle while the nuclear weapons are being perfected" in the United States, Tass said.

But a broader conclusion implicit in attacks on "the insane steps of the Carter administration," Tass said, is that they may have a lasting negative impact both on arms control efforts and on Soviet-American relations in general.

The sharp tone of today's commentaries reflected growing anxiety here that the United States may be moving away from the policy of nuclear parity that has been the basis of Soviet-American strategic arms limitation talks for a decade, and that Moscow may be confronted with new strains on its military budget regardless of the outcome of the U.S. presidential elections.

Thus far, arms talks have been conducted on the assumption that the use of nuclear arms was "inconceivable" since such use would lead to an all-out war between the two superpowers.

Attacking what it called "the blood-thirsty plan for a nuclear attack on another state," Tass said:

"All these actions are sanctioned by the president of the United States, the very president who signed in Vienna a year ago the Soviet-American communique that stressed that there is no task at present more important and urgent for mankind than that of ending the arms race and preventing war.

"It must be said outright that only rabid militarists who have lost all touch with reality and are prepared to push the world into the abyss of nuclear holocaust for the sake of implementing their imperial strivings can conceive and sanction such plans now."

Tass' comment made no reference to the U.S.-Soviet dispute over Moscow's invasion of Afghanistan or to Carter's stated reasons for his policy shifts toward the Soviet Union.

Another Tass dispatch tonight sought to play up the reported differences between Secretary of State Edmund Muskie and national security advisor Zbigniew Brzezinski and Defense Secretary Harold Brown. Tass identified Brzezinski and Brown as the architects of the strategic shift, while it said Muskie, as a senator, had opposed "a similar reconsideration of the nuclear strategy."

The fact that Muskie learned about the strategic change from press reports, Tass said, "corroborates the general opinion" that Brzezinski enjoys "too great influence" in the shaping of U.S. foreign policy.

The tone of today's Tass comments suggested that Moscow regarded the policy shift as a serious matter likely to increase tensions in its relations with Washington.

The shift, it said, "can be explained only by the loss of common sense and the sense of reality in Washington."