Secretary of State George P. Shultz privately appealed to House Minority Leader Robert H. Michel (R-Ill.) this month to oppose legislation that would provide $27 million in aid to noncommunist guerrillas fighting the Marxist government in Angola, but Michel refused, according to correspondence between them.

Shultz said in an Oct. 12 letter to Michel that "in recent weeks" both the South African government, which backs the rebels, and the government of Angola had expressed interest in negotiations. He opposed aiding the guerrillas because a U.S. mediating effort "needs to be pursued forcefully."

But the appeal, in a letter marked "eyes only" for Michel, has touched off an angry response from Michel and other congressional Republicans who are pushing the Reagan administration to provide the nonlethal aid. Michel retorted in a letter to Shultz that the assistance is "not only a geostrategic but a moral necessity."

Shultz's letter, made available yesterday by sources sympathetic to the rebels, comes as the administration is in the midst of a major policy review of whether to aid the noncommunist guerrillas.

At issue is whether the United States should provide either military or humanitarian aid to the noncommunist National Union for the Total Independence of Angola (UNITA) led by Jonas Savimbi, whose guerrilla fighters in southern Angola have recently been under heavy pressure from the Soviet-supplied and Cuban-aided forces of the Marxist government.

Legislation to provide the $27 million in nonlethal aid has been introduced by Rep. Claude Pepper (D-Fla.) and supported by Reps. Jack Kemp (R-N.Y.) and James A. Courter (R-N.J.), among others. Kemp said yesterday he was "deeply disappointed" and termed the Shultz letter "inconsistent with the president's goal of supporting the cause of freedom around the world." Added Courter, "This is not a time to abandon our friend and call for talks."

Shultz's letter, which sources said was not shown to the White House in advance, advocates a State Department view that is not shared by other policymakers in the administration who seek aid for the rebels. Government sources have said that the Pentagon, the Central Intelligence Agency and the National Security Council strongly support military aid, while the State Department has vehemently opposed any shift from the current policy of no assistance.

In July, Congress repealed a decade-old prohibition on aid to the Angolan rebels. That prohibition, named after onetime senator Dick Clark (D-Iowa), was enacted after debate in 1975-76 over disclosures of $30 million in secret CIA assistance to two rebel factions, one of them UNITA.

Shultz said his opposition to the current legislation was based on favorable developments in U.S. efforts to obtain a negotiated withdrawal of Cuban troops in Angola as part of a regional settlement securing independence for South Africa-administered Namibia.

The bill is "ill-timed," he wrote Michel, and "will not contribute to the settlement we seek."

Michel retorted that any attempt by the administration to stop the aid to UNITA would be viewed by the Soviets as "an implicit withdrawal of American sympathy for freedom fighters." He said the situation was similar to that in Nicaragua, where the administration has pressed Congress for nonlethal aid for counterrevolutionaries fighting the Sandinista government.

Michel said aid to the Angolan rebels is supported by "many of my colleagues in the House" and "a majority of the members in our own party."