As interest rates appeared ready to climb still higher, American Bankers Association President Lee Gunderson said yesterday that banks cannot be blamed for inflation or high interest rates. He called on the incoming administration to "send credible signals" of their intention to cut federal spending and reduce the budget deficit.

"Significant federal spending cuts and a sharply reduced federal budget deficit are the basic ingredients for affordable interest rates," he told reporters assembled for the highly unusual press conference in the ABA's Washington headquarters.

Gunderson said the prime rate charged by major banks could go even higher than its present record level of 21 percent. But he refused to predict the eventual peak or to comment on other estimates that the prime could go to 25 percent or higher, saying "who knows what the magic number will be."

Citibank, meanwhile, yesterday raised its broker loan rate to 21 3/4 percent. That is the rate at which banks finance brokers for money they use to finance margin accounts.

Gunderson said he fully supports the Federal Reserve Board's tight-money policy, which has been one element in pushing up interest rates. That policy is "the only game in town attempting to cope with inflation," and it has lead to high interest rates because fiscal policy has not also been restrictive.

Although he urged cuts in spending and in the credit demands of such federal agencies and government related corporations as the Farm Credit Administration, the Federal National Mortgage Association (Fannie Mae) and the Federal Home Loan Banks, Gunderson would not say where he thought cuts should be made.

"It may be a matter of coordination rather than cuts," he said of the agencies. Asked whether he was calling for deep cuts in social welfare payments, Gunderson said, "There are many legitimate needs, but there has to be some opportunity to cut some fat away" without damaging the heart of the programs. He said it was a matter of ordering spending priorities.

"The public should realize that they are competing with the federal government for the available supply of credit," Gunderson told reporters, adding that "as long as the federal debt takes the lion's share of available funds, it will continue to be difficult to find money" to finance other things cheaply.

Federal demands on credit markets fluctuate widely from year to year and depend to a large extent on the state of the economy. In the recession year of 1975, federal agencies and the government together absorbed over 40 percent of the recession-shrunk credit markets, in contrast to only 15 percent the previous year.

From 1977 to 1979 this proportion dropped and stayed at about one-fifth of total credit raised in the United States. Earlier this year the proportion rose again as the sharp recession in the second quarter reduced private demands for funds and raised the government's funding needs.

Gunderson said he did not think that there would be a "sharp" recession next year because of high interest rates but agreed that there would be a slowdown in the economy.

The ABA president said the association wanted to get on record its views about inflation, which he called the major problem facing the country. Gunderson is the president of the small Bank of Osceola in Wisconsin.