President Reagan said today that his Geneva summit meeting with Soviet leader Mikhail Gorbachev was "worthwhile" if only for the agreement to meet again in coming years.

"Well, we got that promise from 'em in a parking lot on the first day we were there," Reagan told a fund-raising luncheon here for Sen. Slade Gorton (R-Wash.).

Reagan said the summit raised hopes for improved relations with the Soviet Union, but he cautioned against ignoring areas of friction between the superpowers. "Geneva let loose a lot of hopes -- mine among them," he said. "But there have been hopeful times before. We have to understand which policies work and which ones don't.

"Blurring the issues and ignoring the areas of friction between the Soviet Union and the United States is no way to create a more peaceful world," Reagan added.

The president's remark on future summits comes as White House officials are working on plans for Gorbachev's visit to the United States next summer. Some officials think that the second summit will create pressure on both superpowers to reach specific agreements on reducing nuclear weapons, which was not accomplished at the first summit.

The president wound up a Thanksgiving vacation at his California ranch today by flying into the teeth of a winter storm and below freezing temperatures here to make the appearance for Gorton, who is expected to face a challenge from former transportation secretary Brock Adams and possibly Rep. Mike Lowry (D-Wash.).

Reagan has been making periodic fund-raising forays on behalf of Senate Republicans in an effort to bolster their prospects next year, when 22 GOP seats are up for reelection and Republican control of the Senate is at stake.

Reagan was expected to raise over $500,000 for Gorton today at a $1,000-a-plate luncheon featuring cold poached salmon and chocolate-mousse cake.

Outside, protestors carried placards urging Reagan to take stronger action to find soldiers missing in action in Southeast Asia. The White House turned down a request for Reagan to meet with Marine veteran Gino Casanova, 34, who has fasted for 48 days in a cage to urge more aggressive action on missing soldiers, according to the Seattle Post-Intelligencer. Gorton visited the veteran last week. White House aides said the president did not have time to meet with him but is concerned about the issue.

On the summit, Reagan said today he "went to Geneva as a first step. I did not expect miracles, but I did expect progress, an opening, a crack in the door, for improved relations," he added.

The two leaders spoke "frankly -- over many hours -- about our differences, about a wide range of issues, including Soviet expansionism," Reagan added. He also recounted how he had presented to Gorbachev his proposed missile defense system, a "space shield" that would render "nuclear missiles obsolete" and thus make them "more negotiable."

"In fact, the progress we made at Geneva was possible only because, in the past five years, we've been determined to make America stronger. That's how the meeting came about. Because we've spoken out clearly about Soviet policies that threaten peace, that policy is working," he said.

On another topic, White House officials today repeatedly refused to comment on a Newsweek magazine report that national security affairs adviser Robert C. McFarlane may be leave his post this year. White House assistant press secretary Albert R. (Rusty) Brashear would not deny the report or say whether it is true. "I'm not talking about it," he said. Other officials have said for some time that McFarlane, who has held the post since 1983, may leave soon.