New York Mayor Abraham D. Beame, who presides over what critics call the welfare capital of the world, said yesterday that President Carter's public assistance plan meets "in principle" the President's campaign pledge to help the city unload its staggering welfare expenditures, but he complained that it does not come soon enough.

"It is clear that there is a need to step up the timetable under which local relief will be forthcoming," Beame said, referring to Carter's suggestion that the program cannot be fully implemented until October, 1980.

New York's $4 billion public assistance budget, which is larger than the gross national products of many medium-sized nations, has been a significant factor in the city's frequent brushes with bankruptcy.

Beame, in a press conference at Gracie Mansion, the mayor's residence, urged that fiscal relief for local governments begin immediately upon enactment of the welfare plan, "rathar than waiting for the implementation of all the complex procedures." Carter said in Plains, Ga., he hoped Congress could adopt the plan by next spring.

Carter said in his press conference that New York can expect $175 million in direct savings as a result of his proposal, an amount that Beame said will allow the city to divert some funds to police and fire services and to reduce taxes, which he said in turn would stimulate new jobs.

Although New York's $14 billion current budget is balanced on paper, the state's Emergency Financial Control Board, which too over much of the city government's fiscal control, said the city faces a $300 million deficit if it falls to impose further economies in the next several years.

Of the total $4 billion federal, state and city outlay for direct welfare payments and Medicaid, New York City's share is $1.1 billion, of which $480 million goes for cash payouts for housing, food and clothing.

The city has 966,000 welfare recipients, or about 12 per cent of all New Yorkers, and the bureaucracy of 28,000 public assistance employees is the largest municipal agency in the world.

However, in the last year New York was able to reduce its welfare rolls by 36,000 persons, after an increase of 10,000 in the preceding 12 months. Beame has pledged to streamline the welfare system, and reduce fraud by such measures as fingerprinting recipients.

Mayoral aides pointed out yesterday that while Carter's promised $175 million fiscal relief falls short of the President's campaign promise that the federal government would completely absorb the city's welfare share "as soon as possible," the amount represents about a third of the welfare costs funded by the city tax levies. Beame had hoped for a 50 per cent absorption immediately, if not a complete federal takeover.

The President, when asked how soon New York can expect the federal government to take the entire load, said he could not answer the question. But he said that federal funds for housing, urban development, jobs programs and public works "far exceed" the city's welfare costs.

Sen. Daniel Patrick Moynihan (D-N.Y.) noted the planned fiscal relief for New York State is $527 million, which he termed, "a very large gain for us, no matter how you look at it."

A third of the net gain, Moynihan observed, will filter down to New York City.

New York City currently pays a fourth of its total welfare cost, which is above the contribution of most other cities. By comparison, Los Angeles funds 12 per cent and Chicago 1 per cent, with the bulk of the burden shouldered by surrounded county jurisdiction.

Moynihan noted that of an annual $5,500 assistance for a New York City family of tour, the federal share now is 50 per cent. Under the revision, the U.S. share will increase to 84 per cent, Moynihan said.

"It's a magnificient program, and very well crafted," Moynihan said in a telephone interview from his upstate New York farm.

Moynihan also said, in response to a question, that New York's high cost of living was not incompatible with Carter's proposed work incentive plan, which would provide welfare recipients public works jobs at the $2.65 hourly minimum wage, plus a 10 per cent state supplement.

A New York City welfare family of four receives about $475 monthly in rent and cash aid benefits, which could amount to more than what a public works job pays after withholding taxes unless the formula is changed.

Rep. Barber B. Conable Jr. (R-N.Y.) said he felt New York City benefits adequately from the plan, but added, "More importantly, the welfare system has got to make sense for the whole country.

"I don't remember Jimmy Carter promising to take on the whole welfare burden of New York, but if he did make such a promise, it shouldn't be carried out, because it would bankrupt the whole nation," Conable said.

"The benefits to New York are somewhat incidental, I don't mean to sound anti-New York City, but I assume the city will continue to handle its fiscal problems with the same level of irresponsibility that it has until now," Conable said.

More important, he said is the need to "come to grips with the tremendous disparity" in welfare distribution. "The last ime I looked, 50 per cent of the welfare of the country was passed out in New York. Massachusetts and California," Conable added.

Beame said that he would continue to press his campaign for 1 million postcards to be sent to the White House by New Yorkers demanding fiscal relief of city welfare costs. The petition campaign, said mayoral aide Sidney Frigand, was begun 10 days ago when the Carter administration seemed to omit fiscal relief, but he said it will continue anyway because "we think the timing of the reform is too sluggish."