Tom Dine, head of the American Israel Public Affairs Committee, startled guests at a private dinner last week when he flatly disagreed with Rep. Steve Solarz that the 1988 election year was no time to launch a U.S. peace offensive in the Middle East.

Democrat Solarz, a liberal leader in the pro-Israel congressional bloc, warned that with Israel also holding a 1988 election campaign, U.S. pressure on hard-line Israeli leaders would make peace moves ''counterproductive.'' Dine, the brainy director of the potent pro-Israel lobby, startled the other guests at Pamela Harriman's Georgetown house by saying, in effect: I disagree. I support George Shultz.

With Rabbi Alexander Schindler, the liberal rabbi from New York, and other Jewish leaders also supporting Shultz's surprise Mideast peace plan in the administration's waning months, the question is, what is the secretary of state's goal? Is it to defuse the Palestinian time bomb and end for now the killings that are damaging Israel's reputation? Or is it an international peace conference and overall settlement?

Dine, Schindler and most other pro-Israel U.S. leaders are silent about supporting basic changes in Israeli policy that the Reagan administration knows are essential for West Bank peace. That suggests their objective may be less than the broad Israel-Palestinian peace Shultz says he is out to get.

If so, despite firm rhetoric and announced purpose, Shultz will seek only short-term measures to end Palestinian deaths and relieve the ugly condition Israel finds itself in today.

The secretary's veiled purpose became all the more obscure with his answers to questions at a private Feb. 9 State Department background session -- the same day Harriman gave her dinner for some of the specialists who attended Shultz's briefing.

He was asked about President Eisenhower's threat to cut off all aid when Israel dragged its feet on withdrawing from the Sinai after its 1956 Suez invasion. Shultz gave no audible reply. But, in fact, no official believes Shultz would risk turning the pro-Israeli lobby against him by threatening Israel's $3 billion U.S. aid package.

Likewise, Shultz is saying nothing, at least publicly, about Israel's ending its colonization of the West Bank and Gaza. Jewish towns that have mushroomed along the high ridges of the land Israel captured in the 1967 war are a major cause of the revolt. Palestinians regard the land as their birthright.

But some officials here disagree that Shultz has suddenly ended years of personal isolation from the Mideast cauldron just to give Israel short-term relief. They argue that he has moved beyond merely appeasing the pro-Israel lobby by trying to end the nightly TV drama of Arab beatings.

''Shultz has the Mideast bit in his teeth,'' we were told by one official, who for the past six years had been trying to convince the secretary to use his personal clout with Israel as he did with the Kremlin over Afghanistan and arms control. He claims the conversion is deep and real.

If so, that might explain the self-confidence that has made Shultz almost exuberant on the Mideast. An official of a former administration suggested to Shultz that he might find it easier to bend Israel if President Reagan invited former presidents Nixon, Ford and Carter to help on a first step: getting Israel to stop building new West Bank towns.

Not a chance, said Shultz. He would not ''cop out'' and he would not ''turn this over to someone else.'' He insisted the job was his and President Reagan's alone.

One participant at the State Department briefing told us the secretary seemed to resent suggestions that he could use the help of the three former presidents. Shultz tells aides that the sole outsider he might recruit is former Mideast envoy Robert Strauss, his close friend and a Democratic insider who is highly regarded by Egyptian President Hosni Mubarak.

But not even his closest aides know how committed Shultz is to the idea of an international conference. Several days after the State Department briefing, Solarz, who was there, told us it was mind-boggling that ''following years of playing Rip Van Winkle on the Mideast,'' Shultz has suddenly admitted during an election year that to get Arab-Israeli peace the United States ''has to be fully engaged all the time.''

That adds a final element of mystery as to what the secretary has in mind. Having played an activist diplomatic role everywhere except the Middle East, Shultz may have acquired a touch of hubris from his proclaimed success in dealings with the Soviet Union and arms control.

But his own record shows how dangerous hubris or even modest confidence can be in the Middle East, starting with the tragic failure of his 1983 Lebanon-Israel accord.