Two key House Republicans urged President Reagan yesterday to make "a major personal commitment" to press Congress for "substantial amounts" of military aid to rebels fighting the government of Nicaragua.

"The current situation in Nicaragua is of grave concern to us," House Minority Leader Robert H. Michel (R-Ill.) and Rep. Dick Cheney (R-Wyo.), chairman of the Republican Policy Committee, told Reagan in a letter.

"It is clear that there are thousands of Nicaraguans prepared to take up arms against the Soviet-Cuban supported regime in Managua," they said. "But their efforts have been limited by a lack of supplies and professional training."

The appeal to the White House on behalf of the rebels, also called contras, came as Colombian Foreign Minister Augusto Ramires Ocampo said that Reagan's insistence on aiding the rebels is incompatible with peace efforts for Central America.

Ramires, in a news conference after talks with administration officials, said the U.S. position toward Nicaragua is "intransigent and extreme" but held out hope differences between the United States and its major Latin American allies could be reconciled.

Ramires is in Washington with foreign ministers from seven other Latin American nations to press the administration to back a new peace plan initiated by the group last month.

The plan calls for a series of steps to be implemented simultaneously by countries involved, including an end to foreign support for guerrilla forces. Ramires said that stopping outside support for guerrillas in the region applied not only to the United States backing for the contras, but also to Nicarguan and Cuban support for Salvadoran guerrillas fighting the U.S.-backed government there. He said, "As long as the United States is asking for aid for the contras, there is not a political climate for national reconciliation."

Under pressure from the administration, Congress approved $27 million in nonlethal aid to the contras last year; it expires March 31. Administration officials have said Reagan intends to make a new bid for as much as $100 million in aid to the rebels, part of it military.