Washington — An alarmed White House is trying retreat from those $100 billion budget deficit figures that loom so menacingly on the horizon. ''There can be,'' says Murray Weidenbaum, ''through spending cuts alone, deficits below $100 billion in each of the next three years.''
Thus the chairman of President Reagan's Council of Economic Advisers (CEA), speaking to reporters at breakfast, knocked down ''raw figure'' projections by the White House budget office that the shortfall could soar to $109 billion this year, $152 billion in fiscal 1983, and $162 billion in 1984.
Those grim statistics, Mr. Weidenbaum stressed, were based on an assumption that Congress and the White House would fashion neither more spending cuts nor tax increases.
On the subject of tax increases, Weidenbaum was cautious, given the fact that his boss - Mr. Reagan - does not like to hear about raising taxes.
Instead, said the CEA chief, a ''solid phalanx'' of budget reviewers - he himself, Budget Director David A. Stockman, and Treasury Secretary Donald T. Regan - was looking at billions of dollars worth of fresh spending cuts for 1983 and 1984.
Enough trims can be forged, Weidenbaum said, to drop the budget shortfall below $100 billion in each of the next three years.
Is he concerned about what the budget cuts are doing to poor, elderly, and other vulnerable Americans?
(Seventy percent of the $35.2 billion trimmed from the 1982 budget came from programs affecting the poor. Some Cabinet officers now are protesting additional suggested cuts in social programs for 1983.
(Health and Human Services Secretary Richard S. Schweiker, for example, objects to - among other proposed cuts - Mr. Stockman's suggestion that the Head Start program for low-income preschool children be phased out.)
Weidenbaum took a moment to answer. ''I am aware,'' he said, ''of the deterioration of the situation of people in our inner cities over the past decade. Is there real distress? Of course.''
But, he asks, have social programs of the past several decades been a real help? He thinks not, citing, not improvement, but deterioration of inner-city conditions.
''So we must try a different approach, while, in the meantime, preserving the social safety-net programs. We need to focus primarily on - how do you solve the basic needs?''
A root need, said Weidenbaum, is to ''create productive jobs in the private sector,'' which he described as the ''fundamental thrust'' of the Reagan program.
Top administration officials, including Weidenbaum and Regan, foresee no collision between the brisk economic growth they expect to begin late next year and restraint on the growth of the money supply.
''From the host of savings incentives afforded (by the 1981 tax bill),'' said Weidenbaum, ''the savings rate will grow.'' He cited the availability, starting next year, of tax-exempt retirement accounts (IRA and Keogh) for almost all working Americans.
Experts expect billions of dollars to pour into these accounts, providing not only a retirement hedge for families but a pool of capital for financial institutions to lend.
Outside the administration many analysts say that spending cuts alone will not suffice to control burgeoning deficits. Some combination of additional measures - a smaller defense budget, cuts in entitlement programs, and tax hikes - will be needed, in this view.
While presenting the ''solid phalanx'' image in public, some of the President's top aides are urging various alternatives upon him - so far without visible success.
Congress, meanwhile, is growing increasingly reluctant to dig deeper into social programs, which already have borne the brunt of budget cutting.
Next month will come at least some public insight into Reagan's approach, when the President sends up to Congress his proposed budget - including a projected deficit - for fiscal 1983.