Nancy Reagan toured the restored house and gardens of impressionist painter Claude Monet today and said they were "so beautiful, I may never leave."

While President Reagan and leaders of six other nations opened their economic summit conference in Versailles, Mrs. Reagan was 50 miles west of Paris at one of France's most prized national monuments.

"She requested to see Monet's house because it's very famous and she likes the paintings of Monet," said Gerald van der Kemp, curator, who spent four years and $2.8 million to restore the picturesque pink stucco house and surrounding gardens.

The property on the bank of the Epte River was where Monet lived from 1883 until he died in 1926. He is buried in the churchyard here.

A painting that Monet did while living at Giverny, "Morning on the Seine," hangs over the mantel in the Vermeil Room at the White House.

At the bottom of the stairway leading into the garden here is a large plaque listing major donors to the restoration effort, including such Americans as Walter Annenberg, Mrs. Vincent Astor, Doris Duke, Charles Englehard, Janet Hooker, Mr. and Mrs. Henry Kissinger, David Rockefeller, Mr. and Mrs. Paul Mellon and Mr. and Mrs. Richard Nixon.

Monet's son, Michel, who died in 1966, gave the property to the Academie des Beaux-Arts and the Marmottan Museum.

"I feel like I'm looking at a Monet painting, don't you?" Reagan said when she saw the water garden where there are clusters of blooming water lilies like those in Monet's paintings.

Before going to the van der Kemp apartment on the grounds, Reagan said she felt as if she had been "taken back in history." When asked if her husband might be jealous of her outings, she said:

"When I tell him about it. We could forget the rest of the trip . I could stay right here."

Last night, she went to the Paris Opera to see a performance of Charles Gounod's opera, "Romeo and Juliet". After the performance she met with the two principals, Barbara Hendricks, 32, of Little Rock, Ark., who played Juliet, and Neil Shicoff, 33, of New York City who played Romeo. Both are graduates of the Juillard School of Music.