In one of the sharpest personal attacks on President Reagan, the official Soviet news agency Tass accused him tonight of trying to organize "an anticommunist crusade" and warned that such policy "may end only in a global catastrophe."

In response to Reagan's speech before the British Parliament on Tuesday, Tass described his approach to world affairs as simplistic, branded him the head "of an administration of millionaires," and questioned the propriety of his remarks.

"One cannot but wonder about the manner in which the American president makes his speeches," said the commentary, which appeared to have been written by a senior Soviet figure. "Crude anti-Sovietism has long been characteristic of Reagan and his immediate entourage. But there is a limit to everything, especially when a person is vested with the powers of a head of state."

The commentary said that Reagan is not concerned about mass unemployment, racism, the arms race, or the suppression of human rights in the West in general and in the United States in particular.

The U.S. president, it added, has divided the world into two parts, one dominated by "totalitarian forces" that are responsible "for all of humanity's conflicts and troubles" and the other led by "freedom forces" headed by the United States.

It said that Soviet President Leonid Brezhnev repeatedly has endorsed "the competition of ideas and systems" and that this "fully accords with detente and peace."

"Yes, the Soviet Union has said and repeats that now," the Tass article continued. "But it proceeds from the premise that the struggle of ideas is not an exchange of nuclear strikes.

"The U.S. president says that a threat of a global war is looming large over the world, but he passes over in silence the fact that the cause of this is the policy of imperialism, above all U.S. imperialism, which has unleashed an unbridled arms race and which is based on the policy of strength in international affairs."

The commentary criticized virtually every point in Reagan's speech, dismissing his remarks as "hypocritical" and asserting that social systems in other countries cannot be "charted by the White House."