Prime Minister Robert Mugabe of Zimbabwe held wide-ranging talks yesterday with President Reagan, and administration officials expressed disappointment with the African country's abstention from the vote on the U.N. resolution deploring the Soviet downing of a South Korean airliner.

Mugabe, on his first official visit to Washington since becoming leader of his newly independent nation in 1980, held what administration sources later described as a "good and substantive discussion" with the president.

"We didn't always agree, but we have all gained much from hearing your views," Reagan told the Zimbabwean premier after a two-hour meeting and working lunch in the White House.

"I believe that our two countries will continue to cooperate in those areas where common concerns are shared and that we will come closer to an understanding on those issues where our views diverge," the president said.

U.S. officials said the two leaders discussed the situation in Chad, where Libyan-backed rebels are fighting the pro-western government; in Central America, and in Namibia, still ruled by South Africa despite western attempts to bring it to independence.

Zimbabwe is opposed to the U.S. position that a Namibian settlement be linked to the withdrawal of Cuban troops from neighboring Angola, arguing that the two issues should be treated separately.

Mugabe told The Washington Post on Monday that he would like the United States to exert more pressure on the white-minority regime in South Africa to expedite a negotiated settlement for Namibia.

"We have enjoyed excellent relations with your country," the Zimbabwean leader said after meeeting Reagan. "There have been differences, on the modality of bringing about Namibia's independence, the linkage with the Cuban question, but generally we have looked at issues through the same glasses."

Mugabe has said he believes the United States could do more to pressure South Africa, but administration officials argue that he exaggerates the extent of American ability to influence the Pretoria regime.

On the question of Zimbabwe's abstention Monday from the U.N. vote on the downing of the Korean plane, officials quoted Mugabe as saying that his country considered itself as representing other nations in the region and they had urged Zimbabwe not to vote for the resolution.

He told The Post Monday that he was concerned by American presentation of the downing of the airliner as an issue in East-West relations, and predicted that Zimbabwe would find it difficult to vote for a resolution couched in terms of what he described as a "superpower versus superpower confrontation."

U.S. officials noted, however, that he referred to the incident yesterday as a "horrible tragedy."

State Department spokesman Alan Romberg said, "Obviously we are disappointed Zimbabwe did not join in, and I would add that the prime minister is fully aware of our views."

Mugabe expressed his country's gratitude for U.S. economic assistance, currently totaling $65 million a year. He met later with Peter McPherson, Agency for International Development administrator.