White House strategists for at least two months have attempted to develop a plan to remit the United States to funnel sophisticated arms and funds clandestinely to African guerrilla forces fighting Soviet-backed Cuban troops in Angola and Ethiopia.

This objective is an underlying motive, according to authoritative sources, behind the frustration expressed by President Carter to congressional leaders on Tuesday. Carter complained about restrictions on White House ability to help beleaguered friendly governments resist communist aggression.

"That was just the tip of the iceberg," one knowledgeable source said yesterday in referring to the accounts that reached the public.

Visible now is the new Western aid and air-rescue mission to Zaire's rich copper belt.

That double operation has been launched with unpublicized apprehension by some officals inside the Carter administration that it is, as one put it, "a first step into the quicksand - on the Vietnam model." Others strongly disagree, insisting that in Zaire the Carter administration is involved only in "aid and humanitarian" objectives.

But apart from what is happening around Kolwezi there is a web of strategic concern especially preoccupying Carter and his national security affairs adviser, zbigniew Brzezinski.

Brzezinski, who left Washington yesterday for China, is described by informed sources as at least as "obsessed" with the Soviet-Cuban projection of military power into Africa as was former secretary of state Henry A. Kissinger over Angola in 1975-76.

To Brzezinski, what is at stake is a fundamental test of the validity of American-Soviet detente, and he is determined to do anything he can to thwart the Russians' Cuban "mercenaries" or surrogates in Africa.

In Peking, Brzezinski evidently will encounter similar attitudes. China has its own anti-Soviet involvement and stake in Africa. The New China News Agency reported from Peking yesterday that in a meeting between Chinese Foreign Minister Huang Hua and Zaire's ambassador to Peking. "The ambassador informed him of the grave situation of the renewed invasion of the Shaba region engineered by the Soviet Union and executed by Cuban mercenaries," and that Huang replied that China will "firmly support" Zaire in its "just struggle to repulse the Soviet-Cuban mercenaries...."

Where Brzezinski and Huang will go from there is an open question.

According to sources in Washington, Brzezinski wants the United States to shake free from the Vietnam war-inspired curbs on presidential power enough to permit U.S. aid for clandestine operations in Africa "to pin down the Cubans" and limit their ability to stretch into other adventures - notably in Rhodesia.

One concept is to furnish sophisticated U.S. weapons, and money, to the supporters of the major guerrilla war that has been continued in Angola since 1976 by Jonas Savimbi's United Front for the Total Independence of Angola. Savimbi's UNITA covertly receives support from a consortium of nations, as well as South Africa.

The nations involved all deny this, when they publicly address the subject at all. The size of "the consortium's" investment is reported by some sources to be in the "$30 million to $40 million range." One Washington source said yesterday "that figure is too high," and other sources put the investment in guerrilla warfare at closer to $20 million.

Another concept that has been pushed behind the scences is to encourage greater covert assistance by Saudi Arabia and other wealthy anti-Marxist nations to the various liberation fronts fighting in Ethiopia's Eritrean Province. Ethiopia this week launched a major offensive to crush that secessionist movement, claiming it has support from the Soviet Union, Cuba, East Germany and other communist nations.

The extent to which President Carter completely shares these perceptions attributed to Brzezinski about what must be done to resist the Soviet-Cuban thrust in Africa is not clear - even to some of the most senior administration officials.

There is burgeoning concern at the top of the administration, (as in Congress) about the scope of Soviet-Cuban adventurism in Africa, among Secretary of State Cyrus R. Vance, Defense Secretary Harold Brown and others, even including many of the pro-Africanists who were dismayed by Kissinger's fixation on the superpower struggle in Africa.

But what is in profound dispute behind the scences inside the administration is what the United States should, or can, do about it. One large fear is that the Carter administration, through preoccupation with Soviet African ventures, may end up jeopardizing the strategic nuclear arms limitation negotiations.

In many respects, the internal struggle of 1975 over clandestine American support to anti-Marxist factions in Angola's civil war is being repeated - but this time more in the open, forced there by the limitations imposed on Angola by Sen. Dick Clark (D-Iowa), chairman of the Senate Foreign Relations subcommittee Africa, and others.

"Let the Cubans have their Vietnam in Africa," one senior administration official pungently said yesterday - "There is no reason for us to get panicked and pluge into the quicksand with them."

This is a predominant view across the State Department, and it is reported no be shared as well by many officials in the Pentagon, and in the Central Intelligence Agency which ran the U.S. venture in Angola that was lopped off by Congress.