A majority of the members of two tax-writing committees of Congress have told President Reagan they will oppose any attempt to eliminate a program that gives businesses tax credits to offset energy conservation costs.

"We are very disappointed that your latest budget package once again proposes to eliminate the business energy tax credits," 18 members of the House Ways and Means Committee wrote Reagan earlier this month.

On Feb. 13, members of the Senate Finance Committee wrote to register their opposition to the Reagan proposal, calling it "an extremely shortsighted action exacerbating the nation's continuing dependence on expensive, unstable supplies of foreign oil."

Earlier, it had appeared that the Reagan administration would try to repeal both residential and business energy tax credits. In the face of considerable opposition to those repeals, the administration narrowed its focus to business tax credits. Tax revisions proposed by the administration would repeal business energy tax credits remaining after Dec. 31, 1982.

The repeal would cover credits for certain types of energy-saving devices, including solar and wind energy property and geothermal equipment, and would increase federal revenues by about $1.5 billion during fiscal years 1983 to 1987. Most of the savings would come from the elimination of credits for biomass equipment and low-head hydroelectric projects, according to the administration.

Reagan administration officials said that the credits--enacted when price controls and supply allocations were in effect--were no longer needed since oil price decontrol means that "most firms confront the true replacement cost of energy and therefore have sufficient incentive to invest in energy conservation and renewable energy and to purchase alternative fuels without targeted tax incentives."