Three Washington area real estate leaders say they are accepting Housing and Urban Development Secretary Moon Landrieu's suggestion that their industry have faith in the real estate market and ride out the current hard times.

Here to attend the annual convention of the National Association of Realtors, the brokers gave these views of the changes that pushed the area's residential real estate market from near-hot to tepid within 30 days.

"I feel better about things now that I've talked to other Realtors and heard some experts express long-term confidence about a short-term situation," said Robert McGrath, president-elect of the Northern Virginia Board of Realtors.

"While virtually nobody is getting the asking price for a home listed in recent weeks, there's still a strong likelihood that houses will appreciate at least 8 percent annually in this area," McGrath said. "That's far from the 15 to 18 percent annual rate in 1977-78, but it's enough to make it worthwhile to buy now at the right price and avoid higher prices in the 1980's."

James Harrison, a Laurel broker and the new president of the Maryland Association of Realtors, said that "Buyers should have confidence in buying shelter for what it really is -- a place to live. Annual appreciation was about 2 percent for many years. I think current appreciation will at least nearly keep pace with inflation.

"Sellers of houses will have to readjust perceived values of their dwellings and accept more realistic prices," he said. "Owners tend to forget that they have lived rent-free for years in a house that has increased in value and provided a tax break along the way."

Kennth J. Luchs, president-elect of the Washington Board of Realtors, said: "We all have been through tough times before. Now sellers have the biggest problems but they can solve them by taking back some financing and being more reasonable in price expectations.

"Buyers? This is always a slow season and a buyer with money should be able to find a good opportunity in this market. Waiting to buy usually has been costly in the long run. Demand is still strong but it's being turned off now. It will break out again and push up prices. That's been the pattern."

At its meeting here this week, the national association approved the purchase of the $8 million, 13-story Wyatt Building at 14th Street and New York Avenue NW for its Washington headquarters. NAR plans to consolidate its Washington staff there in 1981 and sell a smaller building at 925 15th NW that it upgraded several years ago. The national headquarters will remain in Chicago.