Democratic congressional leaders pledged anew yesterday to help push President Carter's new energy plan through Congress, as Carter asked in his news conference Wednesday night, but the effort initially produced only mixed results.

In a series of votes, the House Interior Committee approved a version of Carter's proposal to create a national Energy Mobilization Board to speed development of new energy facilities.

Meanwhile, the Senate Energy Committee voted 14 to 1 to approve the general structure of such a board but failed to agree yesterday on either its scope or power.

At the same time, however, the Senate Finance Committee, irked by Carter's suggestion that it is trying to "gut" his "windfall profits" tax bill, postponed further action until next week, with the prospect of more delays later.

And in response to Carter's Wednesday news conference criticisms, the oil industry launched a counterattack, contending that the proposed windfall tax is not needed and would only inhibit new oil production.

Charles J. DiBona, president of the America Petroleum Institute, the industry's trade group, said the windfall tax would trim any new increase in production by 1 million barrels a day from the 2 million expected by the mid-1980s.

DiBona also pointed out that the oil companies already will be paying additional federal and state income taxes on any increased earnings that result from higher oil prices. Other industry executives issued similar statements.

The new pledge by congressional leaders came in a statement by House Speaker Thomas P. (Tip) O'Neill (d- Mass.) reiterating support for Carter's new energy measures. Carter had accused Congress of "timidity."

O'Neill said he will try again Tuesday for House approval of Carter's proposed standby gasoline rationing bill, which was derailed Wednesday night after Democrats supported a GOP move to weaken the plan.

Meanwhile, Senate Republicans announced plans to try to tack a general tax-cut onto the windfall profits bill when that measure comes to the floor, probably after the August congressional recess.

The scheme is part of a massive "Economic Program for the Decade" which the GOP senators unveiled late yesterday, calling for phased across-the-board reductions in income taxes, a limit on federal spending and new tax incentives.

The senators said in a statement that the administration "seems to lack either the ability or the will or both to deal with" current economic problems. They charged that Carter's policies have bred "a climate of uncertainty . . ."

The House Interior Committee approval of Carter's new Energy Mobilization Board was a partial victory for the administration. However, the measure faces a rival bill by a House Commerce subcommittee that could result in a fight.

Carter proposed the new board as a way to cut through federal, state and local red tape that often slows development of new energy-production facilities. The panel would not have jurisdiction over nuclear power plants.

The decision by the Senate Finance Committee to postpone action on the windfall profits bill was expected. Panel chairman Russell B. Long (D-La.) told Carter on Tuesday the committee would not act until after August recess.

However, it was obvious that Carter's remarks did not please conservatives on the panel. Sen. Bob Dole (R-Kan.) called the president's appeal "an assault . . .against the Congress and specifically the Senate Finance Committee."

Carter had appealed to voters to exert pressure on their senators and congressmen to pass the windfall bill, warning there would be a "a massive struggle to gut" the measure by oil industry lobbying in the Finance Committee.

Although the committee has no formal alternatives before it, panel members have indicated they plan to propose widening the categories of oil that are exempt from the tax to include all newly discovered oil and Alaskan oil.

Senate sources say if the panel approves all of the proposed amendments, it could well wipe out almost all the $142 billion in new tax revenues the measure is expected to yield between now and 1990.

Carter already has complained publicly that two amendments being considered by panel members - exempting small independent producers and phasing the tax out after 1990 - would pare $55 billion from the bill's tax bite.

The president ha s said the monies are needed to finance new energy exploration and production and to underwrite tax credits for the poor to offset the impact of higher energy prices on family budgets.

Dole estimated yesterday that Carter's decision to decontrol oil prices would generate enough added earnings to bring in an extra $173.5 billion in additional federal income taxes from the oil companies between now and 1990.