He hasn't even been hired yet, but last night at a surprise party in his honor Robert G. Neumann, ambassador-designate to Saudi Arabia, already was being put on the spot.

Feted by friends who included former attorney general Mitchell and WRC-Radio talk show host Craig J. Spence as co-hosts, Neumann was asked what he thought about a remark by Saudi Arabia's oil minister, Ahmed Zaki Yamani, the U.S.-Israeli ties posed more of a threat to friendship with the United States than the Soviet Union did.

"I don't think that's what he meant," said Neumann, whose previous experience as U.S. envoy to Afghanistan and Morocco already had taught him a thing or two about diplomatic nuance. "I think the threats come from many directions -- there are countries of dubious friendliness. And nobody knows what's happening in Iran, of course."

(Earlier in the day, Israeli Ambassador Ephraim Evron complained to Nicholas Veliotes, assistant secretary of state-designate for Middle Eastern affairs, that Yamani's comments before a Foreign Policy Association meeting in New York last week had "something very close to an anti-Semitic ring," according to the Associated Press. Last night, Veliotes was among the nearly 200 guests at the party.)

For Neumann, whose nomination went to the Senate only two days ago, the chairman of the Foreign Relations Committee brought word of his chances of being confirmed.

"No longer than it took Secretary of State Alexander Haig and no more difficult than for Deputy Secretary of State William Clark," said Sen. Charles Percy (R-Ill.), and then more reassuringly added, "Our goal is to see that you get a higher percentage of votes in the Senate than any senator in his election."

Later, standing near Club Desiree's buffet table in the Four Seasons Hotel, ABC-TV's Steve Bell told Neumann that the way it sounded to him, Percy's remarks were "an oral contract."

"Have you ever tried to hold a senator to a contract?" asked Neumann, laughing. "Just as long as they don't confuse me with an AWACS."

Nobody confused him with one at the party, but somebody did describe him as a natural resource to be called upon in our time of nee -- it's "fitting to send one of our natural resources to Saudi Arabia."

"If anybody can dance between OPEC and AWACS, you can do it," Spence told Neumann, presenting him a Waterford crystal jar filled with the new national candy, jelly beans.

AWACS wasn't exactly topic No. 1 at the party, but nobody was ignoring the Reagan administration's decision to delay the sale of five radar surveillance planes to Saudi Arabia.

Percy said it was probably wise "because of the Israeli election coming up. The planes wouldn't be delivered until 1985 anyway."

"It will be something we need to negotiate," said Neumann. "And since President Reagan put his authority behind it, we'll make it work."

"Ambushed" by Spence into coming to the party on a pretext that he should meet some visiting Japanese officials, Neumann, 65, was the inspiration for an original poem by John Mitchell: "Here's to your town in Araby, "May the good Lord go with thee. "When your task is done, back in Washington, "May the good Lord deliver thee."

Mitchell's firm, Global Research, with business interests in Saudi Arabia, helped pick up the evening's tab. Among guests were Charles and Susan Ford Vance, Phyllis Schlafly, Saudi Arabia Ambassador Faisal Alhegelan, Moroccan Ambassador Ali Bengelloun, ABC-TV's Ted Koppel, former undersecretary of state David Newsom, Geoffrey Kemp and Richard Pipes of the National Security Council, Peter Krough, dean of Georgetown University's School of Foreign Service, and Prince Faisal of the Saudi royal family.

Spence, a former ABC-TV correspondent who covered the Vietnam war, is director here of the Japan-based Policy Study Group, heads a research-consulting firm and hosts a weekly radio talk show, which is how he met Neumann.

"I wanted to have a send-off for a terrific guy," said Spence.