OSLO, DEC. 10 -- Costa Rican President Oscar Arias, author of a peace initiative designed to end decades of civil war and regional conflict in Central America, was presented with the 1987 Nobel Peace Prize here today.

In a brief acceptance speech before assembled Norwegian notables, including 84-year-old King Olav V, Arias said, "We are all grateful in Central America" for an award that will "enhance the possibilities for success" of the plan.

Speaking in English, Arias said he paid "no attention to those doubters and detractors unwilling to believe that a lasting peace can be genuinely embraced by those who march under a different ideological banner, or those who are more accustomed to cannons of war than to councils of peace."

In an apparent reference to the Reagan administration, which has charged Nicaragua's Sandinista government with imposing a Marxist-Leninist dictatorship, as well as a warning against Nicaraguan interference elsewhere in the region, Arias said "we do not judge, much less condemn, any other nation's political or ideological system, freely chosen and never exported.

"We cannot require sovereign states to conform to patterns of government not of their own choosing," he said. "But we can and do insist that every government respect those universal rights of man that have meaning beyond national boundaries and ideological labels."

The 86-year-old prize consists of of a gold medal and a check for approximately $340,000.

Arias, 46, was named as the prize winner last October. The decision by the prize committee was hailed in most quarters, although it was criticized by some in the United States who labelled it premature.

The Arias peace plan, signed by the five Central Americans Aug. 7, calls for an internal dialogue between each of the warring Central American governments and their unarmed political opposition, a cease-fire and amnesty for rebels and political prisoners, freedom of speech and other peaceful political expression, and free elections held in accord with each country's constitution.