South Africa's white minority government is attempting to roll back a decade of increased black political awareness and expression through the comprehensive attack it launched yesterday on the few remaining groups in the country that advocate multiracial power-sharing.

Most of the organizations outlawed and persons arrested in the law and order offensive are noted for their moderation, their Western middle-class values and their public commitment to achieving charge through peaceful means.

Yesterday's dragnet raids and censorships actions mean in effect that the country's 18 million blacks now have no significant political alternatives left except acceptance of the government's internationally condemned separate development policies or the resort to violence.

Black political parties have been outlawed since the police shooting of black demonstrators at Sharpeville in 1960. The chief targets ofyesterday's moves appeared to be black student and discussion groups that have sought to encourage black pride and consciousness.

But the government also dealt numbing blows to communication between the races and multiracial contract on an equal basis by outlawing the interdenominational Christian Institute and banning the white-owned newspaper The World, which was predominantly but not exclusively staffed and read by blacks.

The clergymen who ran the Christian Institute have sponsored the most serious and detailed criticism of apartheid and its implementation undertaken in South Africa over the past decade.

The World belongs to the white-owned Argus group, one of two newspaper chains in South Africa. Black journalists on The World privately have complained that the paper and its editor, Percy Qoboza, have not been militant enough and even started their own newsletter and journalists union.

The newsletter was banned after one issue in 1976. The union was banned yesterday. And Qoboza, denounced by some of his staff members for being "soft on whites," was arrested for the second time this year.

The government, elected by the country's 4.5 million white population, has demonstrated that the only blacks it will allow to speak with any measure of political freedom are the leaders of the government-created "homelands" to which all blacks are to be exiled politically.

One effect of the government's offensive will be to reassure the extreme rightwing element in Prime Minister John Vorster's Nationalist Party. Vorster is certain to increase his already overwhelming margin in Parliament in elections he has called for Nov. 30, but he is running the campaign as if he is afraid of losing some votes on his extreme right.

American policymakers say they are not sure if Vorster intends to use the sweeping mandate he is seeking from the white electorate to dig in and resist all black dissent and world pressure, or to make major reforms once he is re-elected.