Six figurative bronzes by Alberto Giacometti, examples of the late Swiss artist's "existential" style, have been given by Enid Annenberg Haupt to the National Gallery of Art.

The Giacometti sculptures will be displayed in the Gallery's East Building, which is scheduled to open on June 1. The building was designed, in part, as a magnet for such gifts, and the Haupt donation, which includes a bronze by Henry Moore and a 1954 canvas by Mark Rothko, indicates that the new building already has begun to draw.

Haupt was until 1971 editor and publisher of Seventeen magazine. She is the sister of Walter Annenberg, former ambassador to England, who last March withdrew his offer to establish a $40-million center of art and communications at the Metropolitan Museum of Art. Less than two months later, Anneberg and his wife pledged a cash donation of $2 million to the Philadelphia Museum of Art.

Although she maintains an apartment in Manhattan, Mrs. Haupt said yesterday she did not consider giving her Giacomettis to either the Metropolitan or the Museum of Modern Art."I'll tell you why," she said. "Both of those museums have offered to sell me paintings given them by others. The National Gallery, I'm pleased to see, does not sell works of art."

The Haupt Giacomettis include "The Chariot" and "The Forest," both of 1950, "Standing Woman" (1947), "City Square" (1948-49), "Bust of a Woman" (1956) and "Walking Man" (1960), a 6 foot 2 inch bronze. All these works display the attenuated, roughly modeled, oddly lonely figures for which the artist is best known. Alberto Giacometti 1901-1966) was associated with the surrealists before World War II. The Gallery already owns "The Invisible Object (Hands Holding the Void)" of 1934-35, a sculpture from his surrealist period which was bought, with funds provided by the late Ailsa Meilon Bruce, in 1974.

"The Haupt Giacomettis all are classic pieces," said Gallery curator E. A. Carmean. "'City Square' is probably the most famous. The Chariot" is, however, the one that I like best."

In addition to the Giacomettis, the Rothko and the Moore, Haupt gave the Gallery sculptures by Reginald Butler, Ibram Lassaw, Oskar Schlemmer and a small version of the well known "Horse and Rider" by Marino Marini.

Haupt, 71, who raises orchids at her Palm Beach home, has collected gems as well as art. In 1972, 19 pieces of her jewelry brought a total of more than $2 million at auction in New York. The Washington area has benefited in the past from her generosity. She provided the million dollars with which the American Horticultural Society bought George Washington's old River Farm at Mount Vernon, and in 1967 she gave [WORD ILLEGIBLE] for two fountains between the Washington Monument and the White House.

"Of all my works of art," she said yesterday, "my favorites are my two sketchbooks of Cezanne's. They include 87 drawings. I've discussed them with the National Gallery - I love the Gallery madly - but not yet decided where my Cezannes will go."