The Reagan administration, buoyed by its budget victory in the Democratic House on Thursday, indicated yesterday that it will now hold out against compromise on the president's tax-cut bill as well.

White House chief of staff James A. Baker III said Reagan is standing firm on his proposal for a three-year, 30 percent across-the-board cut in tax rates and will not entertain any bargaining, at least on the plan's major elements.

Meanwhile, House Democratic leaders, will reeling from their defeat on the president's spending proposal, put off consideration of the tax measure until after the Memorial Day recess, partly to give themselves time to regroup.

Democrats on the House Ways and Means Committee were divided over how much of his original tax-cut proposal the president is likely to win intact.

Rep. James R. Jones (D-Okla.), chairman of the House Budget Committee and a member of Ways and Means, said flatly, "If the president puts the same effort into [his tax plan] as he did on the budget, he'll get it."

But Ways and Means Chairman Dan Rostenkowski (D-Ill.) noted that many Democrats who voted to support Reagan's proposed spending cuts in Thursday's balloting have been lukewarm -- or even opposed -- to a sizable tax cut.

"I wouldn't confuse those numbers on the budget vote," Rostenkowski said in a telephone interview. He doesn't interpret it as a signal that any of those members opposed to a big tax cut have changed their minds.

And Rep. Kent Hance (D-Tex.), a key figure in the defection of southern Democrats to the GOP side on the budget resolution, said he didn't think Thursday's vote would spill over and influcence the tax-cut bill.

Several Democratic strategists suggested that Reagan may ultimately want to back away from his three-year plan if Wall Street continues to react adversely for fear the president's tax cut could prove inflationary.

Both Democrats and Republicans on Capitol Hill said they expected Reagan to invite leaders of the House and Senate tax-writing committees to the White House soon to sound them out.

The Ways and Means Committee is slated to begin drafting the tax-cut bill on May 27, almost a month behind its original schedule.Democrats say Rostenkowski's bill could win in committee but lose on the floor.

Reagan has called for a 10 percent cut in individual income tax rates in each of the next three years, combined with faster depreciation writeoffs for business, a package which would total $54 billion in fiscal 1982. w

Rostenkowski has drafted a less costly Democratic alternative that would limit the tax cut only to the current year, tilt the rate reductions toward low- and middle-income people, and provide special relief for tax-payers with interest income and for married couples.

The major battles to be fought are over the size of the cut -- Rostenkowski's plan would cost the Treasury $40 billion -- and over Reagan's insistence on cutting taxes for future years as well as 1981.

Treasury Secretary Donald T. Regan indicated yesterday that while the administration may give ground on a few minor aspects of the tax-cut package, it will stand by its guns on the size and timing of the plan.

However, several Democrats suggested that the president may be more whiling to scale down his tax cut after Congress completes action on the budget measure, which provides room for the full tax-reduction Reagan wants.

Rostenkowski yesterday virtually invited Reagan to discuss the tax-bill situation with congressional leaders, saying such talks would be "a welcome breath of spring" that could clear the air on various key issues.