Washington realtors and bankers, who have been reluctant to make mortgage loan commitments in the city recently because of an interest rate ceiling, were assured yesterday that the present 10 percent rate will be extended and perhaps raised.

The permanent interest rate ceiling in the city is 8 percent, but it has already been raised temporarily to 10 percent. Homeowner mortgage interest rates are already at or near that ceiling in the city, which has been experiencing a boom in construction and renovation.

Upward pressure on the interest rate continues, and in the past, artificially low interest ceilings have resulted in money being transferred to jurisdictions where higher rates can be charged.

City Council member Nadine Winter (D-Ward 6) told a group of local real estate people and mortgage bankers yesterday that the council would extend the temporary 10 percent limit before it expires Aug. 5, and then consider increasing it. "We will get a bill through" extending the limit, Winter said.

"But it is uncertain as to what the ceiling will be," she said. "You will have a ceiling and 11 or 11.5 percent have been suggested."

Lenders have been lobbying for abolishing the limit on the District's usury law, letting rates float with the financial markets, as they do now in Virginia. That is not likely, Winter indicated.

A bill extending the temporary 10 percent limit for 90 days on an emergency basis is expected to be introduced at Tuesday's council session by Wilhelmina Rolark (D-Ward 8). That would give the council time to prepare a permanent increase in the ceiling.

District Building sources, however, say another 90-day extension may be needed, because the interest rate issue is a very controversial one during the race for mayor this year.

City Council member Douglas Moore (D-At Large) has told some lending institution representatives that he favors raising the ceiling to 11 or 11.5 percent.

Fear that the 10 percent limit might not be extended has lead lenders here in recent weeks to make only tentative mortgage commitments to D.C. home buyers. if the ceiling falls back to 8 percent, these mortgages will not be granted.

Even the 10 percent ceiling is limiting the amount of mortgage money available in Washington, lenders say. Mortgage rates have gone to 10 1/4 percent in some areas and lenders say mortgages at less than 10 percent can't be sold in the secondary market.

Mortgage activity in the District also has been slowed drastically in recent weeks by the lack of new deposits in savings and loan associations.

With no new deposits and mortgage rates toolow to be resold in the secondary market, the lenders say they lack funds to make loans.

Raising or abolishing the interest rate ceiling will not immediately send rates soaring, lenders insist. They note that in Virginia, where there is no interest ceiling, rates are the same as in the District or a fraction higher.

And while mortgage money is hard to get in the District now, there are ample amounts available in Virginia, lenders said.