In a sharp rebuke to the Carter administration's policy toward Rhodesia, the House yesterday voted, 229 to 180, to lift economic sanctions against that white minority-ruled African nation at the end of the year if it has installed a new government chosen by free elections.

Such action has been opposed strongly by the administration, which contends that a lasting Rhodesia settlement must have the cooperation of guerrilla forces fighting the transitional government is Salisbury from bases outside Rhodesia.

The administration, in conjuction with Britain, has been trying to force the Salisbury government, dominated by Prime Minister Ian Smith, into an all-parties peace conference with the guerrillas, and argues that continued sanctions are necessary to keep pressure on the Smith regime.

However, yesterday's House vote demonstrated that a significant majority of its members are out of sympathy with an administration policy they apparently regard as weighted too heavily in favor of the guerrilla movements, known collectively as the Patriotic Front.

The Patriotic Front has the backing of the five so-called black African front-line states of the region - an important factor in the administration's argument that no Rhodesian settlement can be made to stick without the acquiesence of the front and its allies.

Despite that point, Congress has shown increasing restiveness at the refusal of the Patriotic Front's two leaders, Joshua Nkomo and Robert Mugabe, to participate in the elections planned for Rhodesia in December - elections that are supposed to give the country its first black-majority government.

In addition, there has been growing criticism is Congress of guerilla incursions, allegedly comitted by the Patriotic Front, which have caused the deaths of several persons, including a number of white missionaries. Conservative members of Congress also have shown concern that Mugabe, who calls himself a Marxist, and Nkomo want to turn Rhodesia into a dictatorship closely allied with the communist bloc.

All of these concerns bubbled to the surface yesterday when the House swept aside the objections of administration supporters and adopted an amendment to the fiscal 1979 military aid bill offered by Rep. Richard H. Ichold (D-Mo.).

The lchord amendment directs that economic and trade sanctions imposed by the United States in accordance with U.N. resolutions must be terminated next Jan 1, "unless the president determines that a new government has not been installed by free elections in whicl all political groups have been allowed to participate freely."

In opting for the Ichord amendment, the House spurned an attempt by Rep. Clement J. Zablocki (D-Wis.), chairman of the House INternational Relations Committee, to push a compromise proposal much more acceptable to the administration.

Zablocki's proposal, which closely paralleled an amendment adopted by the Senate last week, would have given President Carter much more flexibility in any decision to lift sancions. Essentially it would have given Carter discretion to end the embargo if he determined that the Salisbury government had made a good-faith effort to negotiate with the Patriotic Front and then held free elections under international observation.

That approach might still previal when the differences in the House and Senate versions of the military aid bill are ironed out by a conference committee.

In addition, adminsitration sources said last night that, while they will have to study the Ichord amendment more closely, they do not interpret it at a first reading as meanings that the sanctions must be lifted immediately after the new year. They stuck to that assertion despite Ichord's statements that his amendment requires an end to the embargo if she Salisbury government meets the conditions specified by the House yesterday.

However, the significance of yesterday's House action involves not questions of interpretation but a clear sign of a growing rift between the White House and Congress over the administration's Africa policy. That policy, particularly as it applies to Rhodesia and other racial conflicts in southern Africa, has emphasized the need to involve the countries of the region, such as the front-line states, in any solutions.

In yesterday's debate, administration supporters pressed that point, arguing that lifting of sanctions would antagenize U.S.relations with black Africa and the Third World