"An invitation from the White House is a command performance," Calvin Klein decided. So he packed up two 24-karat gold dresses, chartered a plane and took off for Washington yesterday afternoon with two top models, Iman and Lise Taylor.

He and many other designers had been invited to show their clothes at a presentation and reception at the National Arboretum in honor of Mrs. Masayoshi Ohira, wife of the visiting prime minister of Japan. It was the first White House-sponsored fashion event in over 10 years - since Lady Bird Johnson gave one in the State Dining Room of the White House for governors' wives. And if anything could go wrong yesterday, it did.

Rosalynn Carter had chosen to fete Mrs. Ohira with a fashion event since she, like many Japanese women, is greatly interested in fashion. But the date coincided with the peak of the fall shows in New York, so most designers and most of the best clothes were not available.

Aside from Klein, only Adele Simpson, Kasper (with his fiance Sandra Feigen) and Vera Maxwell were present. Halston had to turn down his invitation because he, like Joan Vass, Mary McFadden and Scott Barrie, was having a show in New York almost simultaneously.

Moreover, because buyers are currently reviewing fall collections, designers were reluctant to lend many of their best designs for the show. What did get to Washington was a mish-mash of spring, summer and fall designs from some top names, as well as more volume-price houses.

"We picked the people to whom we had easy access," said Mia Grau, fashion consultant to the International Ladies Garment Workers Union, who coordinated the presentation. As a result, designers such as Perry Ellis were not included because his clothes are made by another union.

Grau placed the fashions in outdoor scenarios around the arboretum. But even before the models got to their places, it started to drizzle. After frantic consultations, Mary Hoyt and Gretchen Poston opted to gamble on the weather.

Mrs. Ohira, who arrived ahead of Mrs. Carter, looked over the models while she waited. She preferred "the wearable things," she said, and gasped over the Calvin Klein dresses. "I had seen gold woven with silk in Japan and that gave me the idea," Klein told Mrs. Ohira, who smiled approvingly.

Before Mrs. Ohira had seen all the clothes, Mrs. Carter arrived and the models were quickly dispatched to their places. Mrs. Carter, (in pink ultrasuede), Mrs. Ohira, (in blue and white silk, and a host of aides and press took off on a tour of the premises to see the fashions as it started to rain a bit harder.

"Hello, I'm a Halston," said one model to Mrs. Carter. "I'm Scott Barrie," said another, referring to the label she was wearing. "I suppose you can turn that dress around and wear it back-to-front," suggested Mrs. Ohira through an interpreter. No, explained Grau, it wouldn't fit quite as well that way.

Klein's models had been planted in a slightly protected area, but as the drizzle became heavier, he raced for raincoats. Klein was taking no chances that his gold dresses might "spoil" in the rain.

By the end of the tour, as the 200 or so guests started to arrive, the rain became still heavier. Umbrellas shot up to protect the hostess and guest of honor, and most of the models dashed for cover and regrouped inside.

American fashion is currently a whopping success in Japan. Mrs. Ohira was familiar with the name Oscar de la Renta and said she had seen his things in Japan.

"Everything American is a status item now in Japan," said Klein, who has been manufacturing and selling clothes in Japan for four years. He's planning a major fashion presentation in Tokyo in September.

But Mrs. Ohira is personally partial to Jun Ashiud and other Japanese designers. And for special occasions, like the official dinner at the White House on Wednesday, she wears traditional kimonos. CAPTION: Picture, Mrs. Ohira and Rosalynn Carter at the fashion show; by Margaret Thomas