House and Senate Republican leaders warned President Reagan yesterday he risks probable defeat on his new round of budget cuts if he submits them to Congress in their present form.

"People up here just don't think it the proposed new cuts will fly," said a GOP leadership aide after the leaders caucused among themselves and then reported the verdict in person to the president.

But there was no immediate indication that Reagan would pull back or modify his proposals. White House aides said he was going ahead with the announcement as planned, probably Wednesday night.

The effort of the Republican leaders to dissuade Reagan came as:

The Department of Health and Human Services, acting on budget cuts already voted, published new regulations that will knock many families off the main federal welfare program. Details, A19

The new chairman of the moderate Republican Ripon Society served notice that GOP middle-of-the-roaders will no longer blindly follow Reagan's lead on budget cuts or foreign policy. Details, A7

Among the congressional leaders, there was reportedly strong sentiment against the president's proposal to save $5 billion--nearly one-third of the $16 billion he wants in new cuts--by delaying cost-of-living increases in Social Security and other federal benefit programs.

The leaders reportedly agreed that any Social Security cuts should come in a bill to shore up the system, not as part of a budget cut.

"I don't think there is any doubt on either side of the aisle, Republican or Democratic, that something has to be done about Social Security. . . but not for the sake of saving money," said Senate Majority Leader Howard H. Baker Jr. (R-Tenn.).

The issue is simply too "volatile," said House Minority Leader Robert H. Michel (R-Ill.).

But Social Security, while the most controversial, wasn't the only problem, the congressional leaders said.

Some Republicans are balking at further cuts in social welfare programs, and many want deeper cuts than the administration is proposing for defense. "I think that's just facing reality," said Michel, speaking of House members' desire for the Pentagon to take its share of budget cuts.

Moreover, several of the House and Senate leaders said Congress is not convinced that the economy, except for soaring interest rates, is troubled enough to justify another wrenching round of program cuts, only two months after it approved a historic $35 billion in cuts proposed by Reagan shortly after he took office.

"A lot of them feel the problems are not as severe as the hype would suggest," said an aide to Michel. Said a prominent House Republican who asked not to be quoted by name: "There was a general consensus that there should be some cuts but not deep ones."

As laid before Senate leaders last week, the draft package included about $16 billion in additional cuts for 1982, adding up to about $75 billion by 1984, all aimed at assuring lower deficits and signaling to the financial markets that Congress is serious about restraining spending and deficits.

The proposals included the cost-of-living deferrals, cutbacks in other open-ended entitlement programs, a phase-out of revenue sharing with local governments, layoff of 75,000 federal workers over three years, abolition of the Departments of Education and Energy as well as 30 to 40 smaller federal agencies and a relatively small cut in spending increases planned for defense ($2 billion in 1982 and $13 billion total over the next three years).

Some of the proposals, especially those dealing with benefit and other entitlement programs, reflected suggestions from Senate Republican leaders. But they triggered a backlash in both houses that resulted in what amounted to a mini-summit meeting of congressional GOP leaders over lunch yesterday in Majority Leader Baker's office. Attending the meeting were the party leadership in both houses as well as the most senior Republicans on committees dealing with budget issues.

The consensus going into the meeting was that the administration proposals were in trouble, and the meeting apparently only confirmed it. Baker and Michel were at the White House within a couple of hours to report their findings to Reagan and his budget high command. The meeting reportedly lasted for more than an hour, with Reagan listening but offering no indication of whether he will modify the proposals to head off obstacles in Congress.

As several sources reported the consensus from the leaders' luncheon meeting, the message was that budget cuts, as presently drafted, might squeak through the Senate but face probable defeat in the House. Many of the leaders also reportedly expressed resistance to the idea of attaching the budget cuts to a stop-gap funding resolution for the government or to a debt ceiling increase measure, both of which must be approved by Oct. 1 to avoid disruption in operation of the government.

The financial markets are already skeptical Congress can bring itself to contain deficits by cutting spending, and it was felt that "the worst thing you could do is send a program up here and get killed," one GOP leadership aide said.

In another development, Republican Reps. Albert Lee Smith Jr. (Ala.) and Richard T. Schulze (Pa.) visited the White House to give Reagan a pledge signed by 155 GOP House members to support any presidential veto of an appropriations bill.