The Reagan administration warned balking Democrats yesterday it has compromised on taxes about as much as it is going to, and indicated it planned no further concessions at a scheduled White House meeting today.

The tough line was taken on television by Treasury Secretary Donald T. Reagan, who was asked by an interviewer if the president might give further ground.

"I doubt it," he said. "You've got to remember, the Republicans did win on Nov. 4, and they won on these proposals. Why should the president go any further in trying to be accomodative to them . . .?"

Regan's remarks, on "Issues and Answers" (ABC, WJLA), came as the president prepared to meet today with leading Democrats from both houses, including House Speaker Thomas P. (Tip) O'Neill Jr. (D-Mass.), to discuss the issue.

At the meeting, Regan said the president will tell the Democrats, "Come on, fellas, time's a wasting; are you going to go with me or do I have to find some other route?"

The White House has already hinted that if it cannot cut a deal with the Hill's Democratic leadership, it might seek the same kind of alliance with conservative Democrats in the House that brought it a victory on the budget last month.

Reagan's initial proposal was for 10 percent cuts in income tax rates across the board, meaning in each income bracket, for each of the next three years. Democrats criticized that as inflationary and tilted too much toward the better off, they have called instead for a one-year cut, structured differently.

The compromise now on the table, Regan said yesterday, although not yet approved by the president, would provide a 5 percent rate cut Oct. 1, followed by 10 percent in July of 1982 and another 10 percent in July, 1983.

Also included are proposals to lower the top tax rate on investment income from 70 to 50 percent right away; to reduce the so-called marriage penalty under which some two-income couples pay more married than they would if single; reduce gift and inheritance taxes, and increase savings incentives by lowering taxes on some interest income.

Reagan originally asked that such proposals be kept for a later tax bill; some members of Congress from both parties wanted them included now.

But this latest version has been rejected by Democrats on the House Ways and Means Committee. During a cacus last week, the panel's 22 Democrats firmly turned down the notion of a multi-year tax cut.

While saying he doubted the president would retreat any further, Regan also described as "minor" the concessions made so far by the administration in what he described as an effort merely to get "a fast tax bill." He called the changes "a little lessening here and a little change there -- nothing that changes the substance of the program."

On another matter, Regan repeated his view that interest rates would soon come down. Based on evidence over the last several weeks that the Federal Reserve Board has been tightening up the money supply, he said, prices are going up and rates starting to go down in the bond markets.

"I think this is the start of a trend," Regan said. "It won't be dramatic at first, but I suspect that by the end of the year, we'll be way down from the rates where we are right now."

In another television interview yesterday, Clifton Garvin Jr., chairman of the board and chief executive officer of the Exxon Corp., said he expects prices for gasoline and home heating oil to be "relatively stable" for the next six months, and possibly longer.

Appearing on "Face the Nation" (CBS, WDVM), Garvin was asked if, in the wake of the decision of oil-producing nations not to raise their rates, Americans might see prices go down a bit.

"Perhaps you will, this is a competitive market that we have in the world," he said. But since the Organization of Petroleum Exporting Countries took no action to reduce the cost of crude oil, he said, "it's unreasonable to expect the price to drop very much."

Garvin suggested that given the amount of excess oil in the world, the current oil glut would probably continue "quite a few months, maybe a year or more" even if the 10 countries that pledged to cut their production actually do so.