The United States has pushed Angola into the arms of the Soviet Union by withholding recognition of the Marxist Angolan government, U.S. Ambassador Andrew Young said tonight.

Young said U.S. policy toward Angola, which achieved independence during civil war four years ago, was prompted by a fear of the 20,000 Cubans estimated to be stationed there.

"I have always felt it is stupid to be afraid of Cubans," Young said. "We should go in there and compete with them."

The Carter administration has made its recognition contigent on the withdrawal of Cuban soldiers from Angola.

"That is one of my biggest regrets," Young said of American failure to recognize Angola during his 2 1/2 years as U.N. ambassador.

Young made the comments at a press briefing following a diplomatic reception at the home of the U.S. ambassador to Kenya, Wilbert J. Le Melle. Kenya is the fifth stop of a seven-nation African trade mission Young is heading.

The trade mission has slipped into the background as the loquacious, outgoing U.N. ambassador increasingly has concentrated his comments on U.S. domestic politics and foreign policy.

Most of his comments have been made in speeches or in answering reporters' questions.

Young's criticism of American policy toward Angola came in response to questions about Young's regret over the death of Angolan President Agostinho Neto. Young said he would have liked to attend Neto's funeral in Angola today.

"I would have liked to have been there because of the respect I have for Neto," he said.

Neto came to power in 1975 as head of the Popular Movement for the Liberation of Angola after more than a decade of anticolonial guerrilla war against the Portuguese. Independence was preceded and followed by civil war between the Popular Movement and two other groups who also had rebelled against the Portuguese.

In the ensuing strife, the United States' Central Intelligence Agency and South African soldiers aided the two movements fighting Neto's Popular Movement. Neto was able to win the conflict with the aid of Cuban soldiers.

Today there are Cuban doctors, technicians and a large contingent of Cuban troops in Angola. The Soviet Union also has large numbers of advisers there.

Angolan "leadership in the frontline states has been the most moderate," Young said. "They want to end the fighting [in Zimbabwe-Rhodesia] because they know the cost."

The front-line states of Angola, Tanzania, Zambia, Mozambique and Botswana have played a leading role in seeking a solution to the guerrilla war in Zimbabwe-Rhodesia.

Young said that while he was a congressman a delegation from the Popular Movement came to see him and asked that the Americans "not do to them what was done to the Cubans."

After it was clear that the Portuguese were leaving and the Popular Movement would win the civil war, "they wanted to stay nonaligned and they felt they couldn't do that if pushed into the Soviet camp," Young said.

Recent news accounts have reported three assassination attempts against Neto by leftists in his own party who wanted a closer alignment with the Soviet Union. Neto is said to have wanted Angola to remain independent of the Soviets.

The withholding of American recognition of their government pushed the Angolans closer to the Soviets than they wanted to be, Young said.

Young said he felt the transition of power to Neto's yet-unknown successor would be smooth. "If there is a smooth transfer and a new government emerges that still wishes to be nonaligned, then I think we ought to give them the chance to be nonaligned," he said.

Young also said Nigeria's transition from military to civilian rule in two weeks, will hvae a wide impact on Africa and other parts of the developing world under military governments. "Freedom is contagious," he said.

Young also said:

Future American foreign policy in Africa will have to include Nigeria, Africa's most populous and richest state.

Nigeria's President-elect Shehu Shagari's incoming civilian government "would be inclined to be a bit more cooperative with Britain" than the outgoing military government, which recently nationalized British Petroleum's holdings in Nigeria.