Beyond Britain's official condemnations of Israel's massive invasion of Lebanon are even sharper sentinments, including a public characterization by Foreign Secretary Francis Pym that the Begin government's actions are "totally . . . grotesquely" out of line with any Palestinian provocation.

These are harsh words that convey bitter feelings. But there is no doubt that in influential government and private circles in Britain today, including some long friendly to Israel, the Begin government is regarded as a major menace. In Parliament this week, Pym accepted another member's assertion that Israeli policy is on a par with the Soviet Union's invasion of Afghanistan.

Nor is Britain unique in this view.The 10 members of the European Community on June 9 "vigorously" condemned the Israeli invasion, calling it a "flagrant violation of international law and . . . the most basic humanitarian principles." Although a move to impose trade and arms restrictions on Israel at a meeting of the Common Market government leaders beginning Monday apparently was abandoned this weekend after several countries expressed reluctance because of uncertainties of the situation in Lebanon, a number of the member countries, including Britain, France and Greece, still favor some sanctions to show their displeasure, even if the day-old cease-fire holds.

The West Germans are reluctant for historical reasons to reproach the Jewish state, but Chancellor Helmut Schmidt is known to feel that Washington should be doing more to bring Begin in line.

Attitudes toward Israel have been hardening in much of Europe for several years, especially since the Begin government's bombing raids on civilian areas of Beirut in the spring of 1981. In Britain, there has always been an Arabist strain among some officials. Pym's predecessor, Lord Carrington, was a prime mover in European efforts to make Palestinian self-determination an integral component of Middle East peace efforts.

What is so striking about the attitude toward Israel now is its pervasiveness. To assail Israel, Denis Healey, deputy leader of the Labor Party, said in an impassioned parliamentary speech Tuesday, is not to be "anti-Israel, anti-Zionist, or still more . . . anti-Semitic. It is perfectly possible for a friend of Israel, as I count myself, to express the gravest concern and dismay at what the Israeli government have been doing."

Even the weekly Jewish Chronicle, a major forum for Britain's 400,000 Jews, declared in an editorial published yesterday that the making of peace now should be the uppermost objective for the Begin government.

But it is at the top levels of Britain's government where the increasing emotion about Israel's invasion is most evident. Initially, the British were restrained by their own problems in the Falkland Islands and the fact that it was the shooting of Israel's ambassador in London, Shlomo Argov, that became a pretext for the military strike at the Palestinians.

Argov is still unconscious in a London hospital. There is no way to judge the extent of his brain damage, sources said, unless he emerges from the coma.

On June 16, right after the Argentine garrison on Stanley surrendered, the first sharp comments about Israel surfaced. Appearing on television, Pym said in response to a question that the Israeli invasion was "grotesquely" disproportionate to the situation. He repeated that view in Parliament this week. Privately, other senior officials began speaking of Israel's pattern of aggression and the need for meaningful restraints to be imposed.

It is Britain's inability to take real action on its attitude toward Israel that plainly adds to the prevailing sentiment.

In addition to the European Community statement, Prime Minister Margaret Thatcher's government has endorsed cease-fire calls at the United Nations, joined in the community's postponement of an economic protocol with Israel and excluded Israel from Britain's annual arms equipment exhibition.

"There is a sense of impotent frustration here," one official said, "watching Israel rewrite the map of the Middle East to its satisfaction." Britain alone has little leverage with the Israelis, and is aware that sanctions by the community are unlikely, mainly because of Bonn's reluctance to reproach the Jewish state.

The burden is not here or in Paris, Bonn or Brussels, British officials say, it is in Washington, the only country able to put a hold on what Begin sees as pursuit of Israel's national interests.

Jonathan Aitken, a well-known pro-Arab, Conservative member of Parliament with strong business connections in the Arab world, was speaking for many more Britons than was once the case when he angrily declared that "the key to the situation in the Middle East is the future of the United States-Israel relationship. At present Washington is letting Israel get away with murder and has been doing so for a considerable time."