Peter Malatesta, the party-giving bachelor who always seemed to know the right people in Washington, was disconsolate last week as he leaned against the bar of Peter's Place, his posh year-old Alexandria restaurant, and tried to explain why he had failed at this, his latest business venture.

"It was," sighed the 45-year-old Malatesta, twisting the blue star sapphire ring on his little finger, "like trying to bring the Rive Gauche to Beltsville."

Malatesta, a pudgy-faced former aide to former vice president Spiro T. Agnew, also happens to be the nephew of comedian Bob Hope, and was able to attract a number of celebrities to his $500,000 suburban watering hole in the heart of Alexandria's Old Town. Hope and Agnew came, as did Lucille Ball, Bert Lance, Hamilton Jordan, Elizabeth Taylor and Pearl Bailey. But the local crowd stayed away.

One Alexandria resident said recently that every time he went to Peter's Place, both the restaurant and the large oval-shaped bar were virtually empty.

"Alexandria is still a sleepy little town," said Taylor Burke, a bank president. "Peter added a little glamor to the town, but I think he was ahead of his time."

Malatesta agreed. "This is a very provincial town. The wealth is grossly exaggerated. They look well, they act well - but they don't spend well," he sniffed. "Alexandria is like Brigadoon - it comes alive every hundred years."

So Malatesta is bailing out of his restaurant having sold his interest to a partner. His departure, however, is complicated by legal and financial difficulties which include a lawsuit by a former landlord and a $25,000 unpaid bill for restaurant equipment.

"We had problems," he said.

On April 20, Gill Co. Inc., one of the city's largest restaurant supply outlets, filed suit in Alexandria Circuit Court against Malatesta and his partner, Hungarian-born developer Arpad Domyan, claiming an unpaid balance of $25,832.16.

Malatesta says the equipment supplied by the firm, red imitation leather banquettes in the bar and dining areas, were not what he had ordered.

A second suit, filed by Alexandria fashion designer Frankie Welch, was dropped when Malatesta settled the overdue bill out of court. "He owed us $1,300," said Welch. "The merchandise was a number of things I designed for his restaurant last year which he gave away as gifts; ties, scarves, cocktail napkins."

In January, Malatesta's former landlord, A. Smith Bowman, filed suit in Alexandria Circuit Court, claiming the restaurateur failed to pay rent from December 1976 to April 1977 on the McLean house Malatesta had rented since 1974 for $1,000 a month. The suit also said the defendant "left the premises in such poor condition . . . as to render it impossible for plaintiff to relet the premises after vacated them."

Specifically, Bowman claims Malatesta owes him $333.35 for swimming pool repair, $5,000 in lawn care, $1,400 to replenish the 3,000-gallon oil tank and other reimbursements. The total is $11,975.

"It was a mess," Bowman said of the condition the house. Malatesta, however, claims he left the house in proper condition, and says Bowman decided to sell the house while Malatesta was still living there.

"I'm not going to discuss it," said Malatesta, "but how would you like it if they started parading buyers in and out of your bedroom in the morning?"

Malatesta - who also owns real estate in California - moved to a house on Queen Street in Alexandria, but gave that up several weeks ago when he decided Old Town was not such a hot town, after all.

"There's no social life here," said the professional party-giver who founded the exclusive Georgetown night club Pisces with Korean businessman and confidant Tongsun Park.

Malatesta also said he had been invited to three Alexandria parties in a year. "They think I'm a snob. And most of my Washington friends didn't want to cross the river. It might as well be New York. I feel too far away. My friends are relieved I'm coming back to Washington. The citizens of Alexandria are too pompous."

Malatesta will take his name to Capitol Hill, where he plans to open a new eatery in November. He also says he is going into the jewelry business.

"I was expecting a lot more (in Alexandria) than Peter got out of it," said developer Domyan, who built the Atrium office complex in Alexandria. Domyan added he was puzzled by the venture's failure.

Malatesta said Peter's Place likely will be replaced by a bar for young singles - a far cry from the swank, celebrity-studded establishment he was offering.

"I'm disappointed, yes," he said over a vodka and orange juice last week, "but not disillusioned."

As Peter Malatesta sees it, the difference between Alexandria and Washington is simple.

"A bridge," he smiled.