White House political director Edward J. Rollins told Republican Party leaders yesterday that they shouldn't count on the economy to improve before the November elections.

"We can't let ourselves get trapped into a false sense of expectation," Rollins said in a speech to the Republican National Committee. "We're still going to be facing high unemployment and high interest rates in November."

Party leaders long have counted on an upswing in the economy in early summer to give a boost to their candidates. They have predicted that dozens of races, particularly in the depressed Midwest, hinge on the economy.

Rollins and Republican National Chairman Richard Richards began a subtle effort this week, however, to convince party leaders not to count on any major improvements in the economy. Instead, they urged party leaders here for a three-day meeting to try to shift the blame for the recession to the Democrats.

Rollins said in an interview that he still hopes the economy will improve in coming months but that he doesn't want GOP candidates to be repudiated by voters if it doesn't.

"The 9 percent unemployment isn't going to drop to 6 percent, and interest rates may drop a few points, but they are still going to be high," he said.

The mood of GOP leaders at the annual summer meting was "optimistic, but not confident," said John Alsop, a national committeeman from Connecticut.

"Everyone, of course, is concerned about the economy and hopes that there'll at least some upswing before fall," said Ody J. Fish, a longtime national committeeman from Wisconsin. "We have a lot of good candidates, and we think we'll do a lot better than people expect."

It was a remark echoed by GOP leaders from many states. President Reagan, they said, remains personally popular, and voters seem to have unusual patience in waiting for the president's economic program to work.

One leader, national finance chairman Richard DeVos, said, "The recession has been a beneficial and cleansing tonic." He also urged the party to ignore organized labor and instead concentrate on the 80 percent of Americans who don't belong to unions.

The only major business yesterday was to name Dallas as the site of the 1984 Republican National Convention, action Reagan requested in January.

The RNC meeting is the most secretive session the party has conducted in recent years. Two of its three days of meetings, which end today, are closed to the media.