President Carter, trying to sweeten his new anti-inflation program, said yesterday he will consider proposing limited tax cuts to stimulate investment and business expansion, but only after he is certain the fiscal 1981 budget will be in balance.

Carter told a cheerless audience at a National League of Cities meeting that "now is a time for discipline -- for all of us -- and not a time for promises or politics as usual." He said "everyone must share in this common effort." Urban aid is one part of the budget he now plans to cut.

The president's remarks came as the nation's financial markets, whose turmoil was one of the major reasons for Carter's policy reversal, reacted negatively to the new anti-inflation plan in their first action since the announcement.

The stock market plunged 23.04 points, with the Dow Jones Industrial Average closing at 788.65, its lowest point since December 1978, while the bond market languished in light trading. In New York, gold closed down $57 an ounce to $469. Only the dollar gained ground. [Details on Page E1.]

Meanwhile, officials disclosed that Carter still has not finally approved any of the specific budget cuts needed to fulfill his proposed $13 billion in spending reductions.

Sources said Carter decided on the $13 billion figure as realistic after discussions in which his advisers outlined $16 billion in potential spending reductions. However, insiders say the president did not actually approve specific cuts.

Insiders say many key cuts are still being debated, as officials seek to soften their impact on cities and various constituent groups.

Carter's chief domestic adviser, Stuart Eizenstat, for example, reportedly is seeking to provide $500 million to $700 million in aid to areas such as New York City to make up in part for a proposed $1 billion reduction in the Targeted Fiscal Assistance program.

Other proposed cuts, such as how much to hold down the growth of the new low-income energy assistance program, still are undecided. Although Congress has developed a list of $18.7 billion in cuts, the White House may not accept all of them.

White House officials also are working to reconcile their budget-cut figures with estimates by various departments and agencies and the independent Congressional Budget Office. Carter has said he will disclose his own proposals in two weeks.

Meanwhile House Speaker Thomas P. (Tip) O'Neill Jr. (D-Mass.) told reporters that Congress will give priority to its own spending-cut proposals when it begins work on the budget this month, rather than waiting for the president's.

Separately, White House economic adviser Charles L. Schultze and anti-inflation chief Alfred E. Kahn ran into opposition yesterday when they tried to explain Carter's new program to key congressional committees.

Kahn also dismissed an estimate by Treasury Secretary G. William Miller that inflation would slow to 11 percent this year as "too optimistic." Schultze told another panel he thought prices would rise 11 3/4 to 12 percent. s

The disclosure that Carter has not formally approved any of his proposed $13 billion in spending cuts came after suggestions in some quarters that the White House was delaying its package to avoid harm in the New York primary. w

Jody Powell, Carter's press secretary, told a luncheon meeting of reporters that suggestions that the delay was political were "the biggest bunch of baloney I've seen in a long time."

"We're doing it as quickly as we can," he said.

However, some administration insiders conceded that the White House was not unmindful of the impact a list of such cuts might have on voting in the New York primary. New York City would be hard hit by the cuts in aid to cities.

Carter's caution against consideration of any tax cuts until after the budget is balanced was intended to head off new efforts in Congress to finance tax reductions from the $11 billion in revenues expected from his new oil-import fee.

Congressional Republicans have been charging that the administration is trying to balance the budget by allowing Americans' tax burdens to rise. Capitol Hill GOP leaders yesterday declared April 15 "National Tax-Increase Observance Day."

Democrats on the House Budget Committee are scheduled to take up a plan today to earmark the import-fee revenues for tax cuts designed to spur business investment and roll back a scheduled 1981 Social Security tax increase.

And Sen. Gary Hart (D-Colo.) has introduced legislation to rebate the oil-import-fee revenues to taxpayers by reducing Social Security taxes. Miller told a television audience on Sunday Carter will resist any such moves.

The plunge in the stock market came as a disappointment to the administration. Only a few hours before, Carter had told city officials the market looked "relatively stable" and said he was "pleased with what has happened so far."

Analysts said it was still too early to judge the reaction in the more crucial bond market, whose teetering on the verge of collapse helped spark the recent policy shift. Schultze told lawmakers several days were needed to gauge the reaction.

Kahn's dispute with Miller over the likely inflation rate this year came at a hearing of the Senate Banking Committee in which the panel handed the administration a victory by coming out foursquare against wage-price controls.

The display of anti-controls sentiment, which emerged informally in comments by committee members, all but ended any chance that the lawmakers might act to impose controls this year. Carter, too, has opposed mandatory controls.

Kakn also told the lawmakers the administration would stick to its spending-cut proposals even if the economy falls into a deep recession, preferring to stimulate production in such a case by cutting taxes rather than new pump-priming.

He also challenged contentions by some economists that cutting spending sharply would not do much to slow inflation. Kahn said such projections were made on computer models that do not take account of today's "different ball game."

Along with the possibility of compensatory aid for a few badly off cities, administration officials still are mulling details of a spate of potential spending cuts, from school-lunch subsidies to public jobs.

Carter has specified only about $3.1 billion of the $13 billion to $14 billion he has said he will cut, including $1.7 billion from eliminating the states' portion of the general revenue-sharing program.

However, officials concede the bulk of the cuts will come from reductions in aid to cities and public jobs programs -- an estimated $1 billion by paring anti-recession aid to locatities, and $1 billion or more in public service jobs.

Finally, Kahn disclosed yesterday that Carter omitted a lengthy admonition about the importance of regulatory reform in his anti-inflation speech on Friday "because two pages stuck together" and he simply missed that part.

Carter also mistook a "3" for an "8" when he looked over the text, telling an audience of dignitaries during his announcement speech that he was proposing cutting $18 billion in spending rather $13 billion.

The White House quickly corrected that, however.