The White House today ruled out the use of U.S. combat troops in El Salvador, but confirmed that a proposal that would permit U.S. military advisers to accompany Salvadoran troops into war zones is under review.

"There is no plan whatsoever to use U.S. troops in a combat role," said White House spokesman Larry Speakes. As to plans to increase the number of U.S. advisers in El Salvador, Speakes said there were 45 there as of Tuesday. "Our initial plan is to make it to 55 and then see how that works," he said.

Speakes also described as "unfortunate" a remark attributed to an unidentified administration official in Wednesday's Washington Post, to the effect that President Reagan had received a negative assessment of the developing Salvadoran situation and would take "all necessary measures" to prevent the country from falling to leftist rebels. Speakes said that instead the administration would do "whatever it can" to help the Salvadoran government.

The White House is trying to steer a fine line between arousing Congress about what the president considers a critical situation in El Salvador and avoiding any suggestion that the United States is becoming involved in a Vietnam-type situation.

Earlier this week the administration asked Congress to approve a request for $60 million in additional military aid for El Salvador.

Assistant Secretary of State Thomas O. Enders, appearing on public television's "MacNeil-Lehrer Report" tonight, said that by the end of this week all of the $25 million previously allocated by Congress for military assistance to El Salvador in fiscal 1983 will have arrived, and that it has all been spent. He said this will leave military stocks of 60 to 90 days if combat continues at current levels.

Yesterday two Republicans, Sen. Mark O. Hatfield (Ore.) and Rep. Jim Leach (Iowa), introduced legislation that would require a cutoff of all military aid to El Salvador and the withdrawal of U.S. military advisers unless the Salvadoran government actively participates "in good faith" in negotiations to achieve a political solution to the civil war.

Their bill would make further security assistance dependent on whether the Salvadoran authorities are willing to open talks "with all major parties to the conflict which are willing to participate unconditionally . . . for the purpose of achieving a cease-fire and an equitable political solution . . . . "

And a third Republican, Sen. David F. Durenberger (Minn.), sent a letter to Reagan saying he will not support additional military aid either unless there is progress toward a negotiated settlement of the Salvadoran conflict.

Durenberger, who said he had been "a consistent and faithful supporter" of Reagan's Central America policy, also strongly criticized recent statements by Secretary of State George P. Shultz and Vice President Bush about the role of the Roman Catholic clergy in El Salvador as "astonishing" and betraying "little understanding" of the church's role in the region.

Both have complained and voiced puzzlement about the fact that Catholic priests are supporting Marxist rebels.

At the Pentagon, meanwhile, an official who briefed reporters on the condition that he not be identified said that under the policy under study U.S. trainers would go only to "safe areas," and he stressed that there would be no change in their role and that they would not go into combat.

He also said it might be necessary to exceed the present self-imposed limit of 55 advisers if the Pentagon is required to train more troops inside El Salvador.

The official, under questioning, said he wasn't sure why the 55-man limit was imposed. "I suppose it was just to pacify those critics who say we're getting involved in another Vietnam."

On another subject, Reagan in a speech here today urged television to cover "good stories" rather than bad news, giving as an example an account of how a barber in Monroe, Ohio, raised $50,000 to build an athletic training center that the local school board couldn't afford.

"I offer this challenge," Reagan said. "April 17 through April 23 is National Volunteer Week. At least during that week, America's heroic private-sector initiative efforts should be given the attention they deserve. Then if the ratings go down, they can go back to bad news."

The text that was distributed before Reagan's speech contained a gibe at some television anchormen that the president did not deliver. The text said " . . . I only wish Dan Rather, Tom Brokaw, Ted Koppel and others in the media would focus a bit more on some of the truly admirable things being done by the American people." Assistant press secretary Anson Franklin said that these words were written by speechwriter Dana Rohrabacher and deleted by Reagan when he returned the speech draft with his revision Wednesday afternoon.

Broadcasters responded critically, nevertheless.

"Politicians are always trying to sell the idea that the only coverage that is fair is coverage that is favorable," Rather said. And Paul Greenberg, executive vice president of NBC Nightly News, said: "We get this from every administration. We led last night with Barney Clark. That's bad news? We had a story about the upturn in the economy. That's bad news? The pope was bad news? What is he talking about?"

Franklin said that Reagan deleted the reference because he considered it inappropriate.