Democratic vice-presidential nominee Geraldine A. Ferraro said today that a recent string of derogatory comments about her by Vice President Bush, his wife and his press secretary were "planned."

Ferraro also said President Reagan's age "is something to be considered" by voters on Nov. 6. Until now, she had assiduously ducked similar questions about Reagan, 73, in the wake of his faltering performance in his Oct. 7 debate against Walter F. Mondale in Louisville.

Ferraro, a three-term House member from Queens, shot back at Bush on another issue, saying the vice president was "backing away" from his charge that Mondale and Ferraro had said U.S. servicemen had "died in shame" in Lebanon.

In the past week, Ferraro has been the target of a string of cutting remarks from Bush and others. The vice president, on Friday, was overheard telling a longshoreman that he had "tried to kick a little ass" in his debate with Ferraro.

That came after Bush's press secretary, Peter Teeley, had said Ferraro was "too bitchy" and after Bush's wife, Barbara, referred to Ferraro as "the $4 million -- I can't say it, but it rhymes with rich." Barbara Bush, who called Ferraro to apologize, said the word she was thinking of was "witch."

"People who have the experience of the Bushes don't do those things unknowingly," Ferraro said at her news conference. When asked how personally she took the comments, Ferraro added with a smile, "Today I'm not offended. Tomorrow I might be."

Asked during a question-and-answer session at the Cleveland City Club about the "age" issue, she said, "That's not a judgment that I should make, with reference to the president's age. I think that that's something the American public has to take a close look at and consider, or not consider, whether it's important or not important.

"I think it is something to be considered," she added. "But again, it is something you the public would make the determination on."

In a subsequent news conference, Ferraro, 49, qualified her statement somewhat by suggesting that age "is just one of the factors that should be considered along with everything else." Asked if she had intended to portray Reagan as too old to be an effective chief executive, she said, "If that's the impression I left, I'm sorry."

On Bush's charge that the Democrats had said U.S. servicemen "died in shame" in Lebanon, Ferraro said: "This is not the first time that Mr. Bush or Mr. Reagan or someone in the administration has distorted what Fritz Mondale and I have said. It also is an indication of how this administration has operated over the past four years. They make a mistake, and they don't admit to the mistake, and then they don't learn from the mistake."

Asked whether she wants an apology from Bush, she said, "It's not Gerry Ferraro who deserves an apology. It's the American people."

Of the servicemen killed in Beirut she said, "They didn't die in battle. They didn't die fighting. They were victims. And that's terrible. This administration, instead of walking away from it . . . should address the problem and do something about security for both our armed forces and Americans living abroad."

Meanwhile, Ferraro campaign officials said they were offended by a decision this week to exclude her from the annual Al Smith dinner in New York Thursday.

According to campaign manager John Sasso, Ferraro's aides last week asked that she serve as a surrogate speaker for Mondale, who will be preoccupied with preparations for his debate Sunday with Reagan. Organizers of the dinner turned down the request.

Privately, Ferraro aides say they suspect that the snub was orchestrated by Roman Catholic Archbishop John J. O'Connor of New York, who has feuded with Ferraro over abortion.

"There was no snub intended by the archbishop," said Joseph Zwilling, assistant director of communications of the Archdiocese of New York. "Traditionally vice-presidential candidates in an election year do not come."

In 1972, Vice President Spiro T. Agnew attended in place of President Richard M. Nixon. Zwilling said that in 1972, instead of presidential candidates, the dinner invitation listed Kurt Waldheim, then secretary general of the United Nations, as the main speaker.