The Carter administration yesterday intensified its show of disapproval toward the new military regime in Bolivia by cutting off economic assistance, pulling out U.S. military advisers and sharply cutting back the U.S. embassy staff in that beleaguered South Americian nation.

The U.S. actions were announced by Secretary of the State Edmund S. Muskie just hours before the Organization of American States, meeting here, voted 16 to 3 with four nations abstaining, to deplore the week-old military coup and to express its deep concern over the loss of life and human rights of the Bolivian people.

The Bolivian armed forces, led by a junta of three top military commanders, overthrew the interim president, Lidia Gueiler, last week in an effort to prevent former leftist president Hernan Siles Zuazo from returning to power.

The United States recalled its ambassador to Bolivia and cut off military aid immediately after the coup. Yesterday's actions accelerate the administration's campaign against the new regime and could add to Bolivia's economic difficulties.

Muskie said the new steps were taken "to demonstrate the depth of our concern" over the military takeover. He said, "Bolivia's democratic process has been thwarted. The will of the Bolivian people, freely expressed in recent elections, has been flagrantly violated."

The United States, he said, "cannot support this attempt to thwart the will of the Bolivian people."

The quick administration reaction to the events in Bolivia fits into a new U.S. policy in both Central and South America that is aimed at giving strong support to democratic change in the region, in the hope it will not turn communist, while ending the longstanding image of the United States as a backer of military dictatorships in the region.

Muskie said he had ordered "the termination of all economic assistance projects where there is a basis to do so under existing agreements."

The cutoff, he said, does not include food aid and other humanitarian projects.

The United States has been providing Bolivia with about $20 million annually in direct economic and development aid. About $115 million in such aid had been previously obligated but not yet spent, and much or all of this money will also be shut off,presuming "that there is a basis to do so under existing agreements," according to Muskie.

State Department officials were unsure late yesterday exactly what that phrase meant, though it could imply a legal review to see how much aid actually could be stopped.

The U.S. military group to be pulled out includes all eight advisers, and officials say the cutback in the 112-member embassy staff will be substantial.

The OAS resolution also called for the Inter-American Human Rights Commission to examine the situation in Bolivia as soon as possible.

The United States and four of the five Andean Pact nations -- Venezuela, Peru, Columbia and Ecuador -- were among the 16 nations that voted for the OAS resolution. Bolivia, the fifth Andean Pact country, voted against the resolution, along with Chile and Paraguay.

Brazil, Argentina, Guatemala and Uruguay abstained.

Meanwhile, West Germany announced it has recalled its ambassador to Bolivia for consultations, but said that for now it will continue development aid to that country.