The Soviet government asserted today that Western nations would assume "grave responsibility" if they "destroy the basis" for Soviet-American arms control negotiations.

In a statement distributed by the government news agency Tass, the Kremlin said that Western nations "need" these negotiations as much as Soviet Bloc countries because the future of mankind is at stake.

Assailing the decisions by NATO foreign ministers earlier this week, the Soviet Union said that "it is not fortuitous" that the NATO communique contained "hints" that the United States could break off the nuclear talks "if matters in Poland develop not the way some people at NATO would like."

"One thing must be said in this connection," the statement said. "The capitalist countries need an end to the arms race, prevention of war . . . not less than the Soviet Union and its friends if, to be sure, one is seriously and truly concerned with the future and does not act like venturesome gamblers who are prepared to stake everything and rush blindfolded into an abyss.

"And at stake in this case would be the destinies and the life itself of the peoples and of the entire mankind."

The statement again focused its criticism of the NATO decision exclusively on the United States. It said, "This disgraceful farce had been initiated by the Reagan administration."

In words seemingly directed at West European public opinion, the statement said that the Reagan administration "artificially dramatized" the Polish crisis to create greater East-West tension.

The statement said, "No hostility to socialism . . . can overshadow the problems of war and peace and of ending the arms race and first of all the nuclear missile arms race. To destroy the basis of talks on these problems would mean to assume grave responsibility."

It asserted that the military takeover in Poland was "a matter of the Poles and of them alone."

But, it added, "at the same time, it should be clear that the Soviet Union is not indifferent to the fate of neighboring socialist Poland . . ."