U.N. Ambassador Jeane J. Kirkpatrick told Congress yesterday that American support for the people of Afghanistan is "a moral and geopolitical necessity," but "victory or surrender are not the only alternatives" for ending their struggle with Soviet occupying forces.

"We believe there is a basis for an honorable solution which serves the interests of all parties," Kirkpatrick said.

The outgoing envoy was referring to the administration's four-point plan to achieve negotiations on ending the Soviet occupation.

The plan calls for immediate withdrawal of Soviet troops that have been in the country since December 1979; preserving the independence and nonaligned character of Afghanistan; allowing the Afghan people to determine their form of government and economic system, and permitting return home of thousands of Afghan refugees in neighboring Pakistan and elsewhere.

Kirkpatrick testified before the Congressional Task Force on Afghanistan, a joint House-Senate group headed by Sen. Gordon J. Humphrey (R-N.H.).

"The Afghan people have been gassed, bombed, buried, driven from their homes and now they may be starved," Kirkpatrick said in describing Soviet efforts to quell the Mujaheddin, or guerrilla forces.

"It seems likely that the Soviet goal in Afghanistan is incorporation of Afghanistan [into the Soviet Union] and achievement of a warm-water port and geopolitical access to Iran and Pakistan," she said.

"The resistance of the Afghan nation to incorporation, its struggle to survive, is a challenge to the carefully cultivated image of Soviet invincibility," Kirkpatrick said. "But Soviet triumph in Afghanistan is not inevitable. Defeat of the Mujaheddin is not inevitable. The expansion of Soviet power in the region is not inevitable."

As to what the United States and other western nations should do, she said that "obvious appropriate responses" should include humanitarian assistance, diplomatic solidarity with refugee efforts to plead their case before the world and support for U.N. efforts to prod the Soviets and other interested parties toward negotiations.

In what appeared to be a reference to covert U.S. supply activities for the guerrillas, she added, "Obviously all appropriate forms of assistance to those seeking to ensure the survival of Afghanistan are important and must be undertaken."