WASHINGTON (AP) _ Republican officials, having asked 11 cities to meet specifications for the 1988 GOP convention, are trying to end speculation that an unwritten standard is the approval of Nancy Reagan.

Terry Wade, communications director of the Republican National Committee, called reporters Monday to say that RNC chairman Frank J. Fahrenkopf Jr. had talked to the first lady and ''she said she did not have a preference.''

''I just know Mrs. Reagan hasn't given any thought to the convention and will go along with the decision of the committee,'' said Elaine Crispin, the first lady's press secretary.

Ms. Crispin said that ''for about a month now we've been reading these little trickles.''

Those trickles are the continuing speculation that Mrs. Reagan would like the 1988 convention held in Los Angeles, the city the Reagans consider home.

Fahrenkopf tried to dampen that speculation last Thursday when he held a news conference to announce that specifications for the convention had been mailed to 11 cities that had expressed interest in being the site.

In addition to Los Angeles, the candidates are Atlanta, Detroit, Houston, Kansas City, Mo.; Las Vegas, Miami, Philadelphia, San Diego, Seattle and St. Louis.

''There has been a great deal of speculation that this committee has already made up its mind,'' said the chairman. ''It's not true.''

Fahrenkopf said he had been assured that President Reagan has no preference.

Did that assurance come from the president himself?

No, said the chairman, it came from White House staff chief Donald Regan.

What about Mrs. Reagan, was the next question.

''I haven't talked to the first lady,'' Fahrenkopf replied.

Wade said Monday that the chairman was concerned that ''the way he answered the question put it up in the air.''

Fahrenkopf talked to the first lady the next day and was anxious to get word out that she had no interest in where the convention is held. He wanted ''to put it to rest,'' Wade said.

The process of screening bids for the convention is the hands of the party's site selection committee, made up of eight members of the RNC and Fahrenkopf.

The panel had its first formal meeting before Fahrenkopf's news conference Thursday.

Ebbie Spivey, chairman of the Mississippi Republican Party and a member of the selection committee, said: ''Someone had a copy of the morning paper, I don't even know which paper it was. At any rate, there was a small paragraph in there saying the site committee of the Republican National Committee is meeting this morning. The Republicans have decided to go to Los Angeles and it is known that the Democrats are going to Atlanta.''

Mrs. Spivey added: ''We had not even begun our meeting. I can see where the chairman would be concerned. We all thought it was a hoot. We had not made that decision at all, not one of us.''

''I really don't believe the president is going to get involved,'' said Carl J. Gillis Jr. of Adrian, Ga., another member of the selection panel. ''Because if he was, he's a pretty square shooter if he was going to do something and it was going to hurt your feelings, he'd do it now rather than wait until we go and visit with all these cities.''

Mrs. Spivey said, ''My feeling is if the president decided he thought California would be a good place - most of us are very proud of President Reagan - if that's what he chooses that would be fine with us.

''However, he has made it very clear he has no intention of making that decision for us.''

The Democrats are at about the same point in their selection process as the Republicans. Both parties expect to receive the recommendations of their selection committees by the end of this year.