First Daughter Patti Davis, on a national tour to promote her novel, "Home Front," was dropped hours before scheduled appearances on talk shows hosted by Joan Rivers and Merv Griffin, spokesmen for the shows confirmed yesterday.

The last-minute cancellations sparked speculation that the Reagans had pressured the two stars not to interview Davis, but the White House yesterday denied any involvement.

"We tried to do some digging into what was behind it but we couldn't get too many answers," Nancy Kahan, associate publisher of Crown, which published "Home Front," said yesterday.

"We did hear from someone on the coast that Nancy Reagan had made a call to Joan Rivers, but there was no way we could verify it," she said. "We understood that Joan said it was too late to cancel the show sk,1 sw,-1 and that she suggested doing the interview but not mentioning the book. The response was 'Don't do the interview.' "

Nancy Reagan's press secretary, Elaine Crispen, said no such call was made. "It wasn't Mrs. Reagan, this office or anyone I know of from the White House," Crispen said. "We had nothing at all to do with Patti's book tour, or with the cancellations."

Spokesmen for Griffin and for the "Tonight" show, which Rivers was hosting, said the stars had read and disapproved of the book, which is the story of a rebellious young girl whose father moves from the California statehouse to the White House.

Davis did appear on the Donahue show last week. A spokeswoman confirmed that Phil Donahue had said later that "an effort was made to discourage us from doing the show," but that the pressure did not come from the Reagans or anyone in the government.

Word of the cancellations spread after Davis told syndicated columnist Liz Smith about them on Friday.

Davis, who was in Chicago yesterday for an appearance on the "Oprah Winfrey Show," could not be reached for comment. She did, however, comment on the air there about her aborted appearance with Rivers on the "Tonight" show. "I guess she's entitled to interview whoever she wants," she told Winfrey. "I've heard some of her routines and it doesn't seem she spares her daughter anything."

Rivers is known to be very fond of Mrs. Reagan, and one mutual friend said it isn't inconceivable that the comedian might try to protect the first lady by canceling the appearance.

Crispen said Rivers has attended a state dinner at the White House and also entertained in the first lady's honor at the Republican National Convention in Dallas.

She also said the friendship with Griffin "goes back a long time. They share a birth date, but I don't see any connection in this."

Both President and Mrs. Reagan have read the book and called it an "interesting novel, interesting fiction," but White House insiders have described them as "hurt" by it.

Davis has not seen her parents since starting the tour although she came to Washington Friday night to appear on the Larry King radio and television shows. A spokeswoman said Davis, who stayed at the Sheraton Grand Hotel on Capitol Hill and left early Saturday morning, told King that she does not drop in on her parents unexpectedly.

Rivers was promoting Davis' scheduled Thursday appearance on earlier "Tonight" shows last week. Davis flew to Los Angeles from the East Coast to keep her date, but she was informed two hours before she was scheduled to appear that she need not show up.

"The 'Tonight' show said they were sorry but that Joan had read the book and felt, as a wife and mother, she couldn't do the interview," said Kahan.

Rivers did not explain Davis' absence on the show that night, although that is customary when there is a cancellation. Spokesmen for the "Tonight" show and for Rivers had different versions of who was responsible for booking Davis.

"Tonight" show executive producer Fred de Cordova said, "The show's staff does not book anybody who is not suggested by the host or hostess, or is not discussed in advance by the host or hostess.

"I've known Miss Davis for a long time and I would not want her to think I initiated the events. She is a friend and so are her parents," said de Cordova, who directed Reagan in the 1951 film "Bedtime for Bonzo."

De Cordova also said he knew of no one who had received a request to "negate the booking."

Richard Grant, Rivers' publicist, said, "I don't care what they're saying. Maybe for some strange reason they're trying to pass the buck. Miss Rivers does not book guests. On many occasions she has recommended guests and her recommendations have been turned down."

A spokeswoman for Merv Griffin said Griffin decided to drop Davis as a guest from a show in late February after reading her book.

"He didn't want to promote the book on his show. Knowing him, he probably didn't read the book until the last minute," said Linda Dozeretz of Rogers and Cowan, which handles Griffin's public relations.

As far as Davis' publishers were concerned, the turn of events seemed to be working for rather than against her.

"If one had planned for something to happen to help a book sell, it couldn't have been more perfectly orchestrated," said Kahan.