The Democratic-controlled House voted yesterday to end a decade-old prohibition on U.S. military assistance to guerrillas fighting the Marxist government of Angola.

The Senate took similar action last month.

As recently as 1981 the House opposed repealing the ban, known as the Clark amendment, and opening the door to possible new U.S. involvement in Angola. However, lawmakers now appear to be in a more hard-line mood regarding defense and foreign-policy issues and more eager to assist anticommunist insurgency groups around the world.

Earlier this week the House voted overwhelmingly to provide overt assistance for the first time to noncommunist groups fighting Vietnamese troops in Cambodia. And last month the House reversed itself and agreed to provide aid to counterrevolutionaries fighting the leftist government in Nicaragua.

Yesterday's vote on Angola was 236 to 185, with 176 Republicans and 60 Democrats voting in favor of lifting the ban on aid, and six Republicans and 179 Democrats opposed. The amendment, sponsored by Rep. Samuel S. Stratton (D-N.Y.) and attached to the 1986 foreign-aid bill, does not provide military aid to any group, but gives the Reagan administration the authority to request it.

The Clark amendment, named after former senator Dick Clark (D-Iowa), has been in place since 1976. The Senate voted to repeal it in 1981, but the House balked.

The amendment was adopted after the Vietnam war in response to revelations that the Central Intelligence Agency had provided covert military aid to pro-western groups fighting Marxist nationalist forces during 1975 and 1976 in the midst of a civil war in Angola.

The administration favored repeal of the amendment but White House officials have said there are no immediate plans to request military or other aid for the pro-western National Union for the Total Independence of Angola (UNITA), led by Jonas Savimbi, which continues to fight Angola's Cuban-backed government.

The United States has no diplomatic relations with Angola but has been seeking its cooperation for a peace plan that would couple the withdrawal of 25,000 to 30,000 Cuban troops from Angola with independence for its neighbor, the South African-administered territory of Namibia.

Talks to accomplish this stalled in May when South Africa launched a commando raid on a Gulf Oil facility in Angola.

Lawmakers favoring repeal of the Clark amendment said yesterday that the legislation is out of date now that Congress is willing to provide aid to other anticommunist insurgency groups and that a peaceful settlement in southern Africa is not possible so long as Cuban forces remain in Angola.

"As long as those Cubans stay in Angola there will never be any peace there" and the Angolan people will "never be able to remove the yoke of communism," Stratton said. "We are providing help to those who are fighting the forces of communism in every area of the world . . . even Cambodia," so why not Angola, he asked.

Opponents argued that repealing the amendment would hurt the peace process at a time when the Cubans have indicated that they have a timetable for withdrawing their troops, and would further align the United States with the repressive South African regime.

Rep. Ted Weiss (D-N.Y.) said that repeal would show that "our obsession with communism is such that we will do anything and everything, even if it hurts the people we want to help."

Earlier yesterday, the House voted to deny federal aid to private international organizations that perform or actively promote abortion as a family-planning method. It also adopted an amendment accusing China of "crimes against humanity" because of the coerced abortion and sterilization aspects of its of its population-control practices.