The collapse of Prime Minister Bettino Craxi's government following a bitter row between Rome and Washington over Mohammed Abbas, a Palestinian official wanted by the United States, triggered a surge of anti-American sentiment in the national media today and concern among political leaders.

The outbursts came as President Francesco Cossiga met with previous Italian heads of state and legislative leaders before opening consultations Saturday with political figures on forming a new government, Italy's 45th since the end of World War II.

The likelihood, political observers said, was that he would ask Craxi, Italy's first Socialist prime minister since the war, to try to form a new government to replace the 26-month-old, five-party coalition that collapsed this week after the withdrawal of the Republican Party. The small, pro-American party pulled out because of Craxi's refusal to detain Abbas for possible extradition to the United States.

Underscoring officials' concerns at the anti-American commentaries, Socialist Giovanni Amato, the influential undersecretary of state in the prime minister's office, said that "the real tragedy in this affair is that we have been working for years to destroy the kind of anti-Americanism in any and all nations in this region that have a strong left.

"It would be a tragedy," he said in an interview today, "if that anti-Americanism begins again because of U.S. government mistakes this past week."

The dispute between the Craxi majority and the Republican Party of Defense Minister Giovanni Spadolini ostensibly was over a lack of consultation over the hijacking and the Abbas affair.

The real dispute, according to observers and analysts here, had much to do with the animosity between Spadolini -- whom Craxi replaced in 1983 -- and the prime minister and the divisions between the two over Italy's policy in the Middle East. Spadolini has favored a pro- Israel line while Craxi and his foreign minister, Giulio Andreotti, a Christian Democrat, have followed a more pro-Arab stance.

The U.S. government has claimed that Abbas, 38, leader of a faction within the Palestine Liberation Front, was the mastermind of the hijacking of the Italian cruise ship Achille Lauro 12 days ago during which a U.S. passenger, Leon Klinghoffer, 69, was slain. The Italian government has maintained that the United States failed to provide enough evidence to substantiate its case, and Italy allowed Abbas to leave for Yugoslavia last Saturday. His current whereabouts are unknown.

The fallout from the case that brought down one of Italy's most stable postwar governments has prompted concern about the future course of Italy, one of the United States' most loyal European allies.

Tonight the Italian news agency ANSA said it was "extremely problematical" for Craxi to travel to the United States next week for a speech at the United Nations and a meeting of five allied nations called by President Reagan before next month's U.S.-Soviet summit. France has declined to meet with Reagan.

The demands the United States made on Italy in the case -- and the way in which they were made -- were condemned today by this country's leading publications, ranging from right-of-center newspapers such as Il Giorno to L'Unita, the official paper of the Italian Communist Party.

The influential left-of-center La Repubblica, one of Craxi's most consistent critics, denounced U.S. behavior as "arrogant" and "heavy-handed." Its respected deputy director, Giampaolo Panza, spoke of the "impatience and harshness of the emperor" Reagan, whose only saving grace was that he was more "Rambo than Strangelove."

Vittorio Emiliani, editor in chief of Rome's moderate Il Messaggero, the capital's largest circulation daily, said Italy's troubles this week were caused because the Italian government refused to act like a "banana republic."

The weekly news magazine L'Europeo was more graphic. Its latest edition, which hit newsstands today, was wrapped in a colored cover that showed a cowboy-clad Reagan spanking a bare-bottomed baby whose face was that of Craxi.

In an explanation to the Italian Parliament of his government's actions, Craxi criticized the United States yesterday for infringements on Italian sovereignty during the crisis and its efforts to force the Italian government to act against its own laws with respect to Abbas.

Abbas, a Palestinian aide and the four hijackers were forcibly brought to Italy a week ago in an official Egyptian jet that was intercepted by U.S. Navy fighters as it sought to fly from Cairo to Tunisia. The jet was diverted to the joint U.S.-Italian naval air station on Sicily.

Although Craxi allowed the jet to land when belatedly informed of the interception in a telephone call from Reagan, he explained yesterday, he refused to allow U.S. commandos who landed, unannounced, behind the Egyptair Boeing 737 to take the hijackers, Abbas and his aide to the United States.

While Craxi said he accepted the "emergency situation" of the U.S. action and welcomed the fact that the four apparent hijackers had been returned to Italian soil, the real problems developed later over the presence of Abbas aboard the plane.

In his remarks to Parliament yesterday Craxi alluded to a tense three hours in which the U.S. Delta Force commandos, led by a U.S. general in direct radio contact with Washington, faced down a group of Italian soldiers surrounding the Egyptian jet. Italian sources said that the American general was prepared to storm the plane despite the Italians' protest, until Reagan was persuaded by Craxi, in a later telephone conversation, that the hijackers had to be tried in Italy.

The confrontation did not end there, however. Craxi charged that the United States violated Italian airspace when it was decided to fly the Egyptian airliner -- without the hijackers but with Abbas, his aide and Egyptian officials aboard -- from Sicily to Rome last Friday.

Craxi accused the United States of sending an F14 from Sigonella to tail the plane to Rome without authorization and despite the fact that the Egyptian plane was escorted by four Italian fighters. A second unregulated U.S. jet, a T39, according to Craxi, landed at Ciampino and taxied close to the Egyptian airliner.

[In Washington, an administration official said an unarmed Air Force T39 training plane followed the 737 to Ciampino but denied that an F14 was also tailing the Egyptian plane.]

Staff writer David B. Ottaway added from Washington:

President Reagan sent a high-ranking administration emissary to Italy and Egypt today in an apparent bid to smooth strained relations with the close U.S. allies in the aftermath of the Achille Lauro hijacking.

A State Department spokesman said Deputy Assistant Secretary John C. Whitehead departed tonight on a "presidential mission" for a three-day visit to Cairo, with a stopover in Rome Saturday.

The spokesman said Whitehead would meet with Italian caretaker Prime Minister Bettino Craxi and other Italian officials "to discuss issues of mutual interest" with "an important friend and ally with whom we consult on a regular basis."

The spokesman stressed that U.S.-Italian relations "have been and will remain broad, deep and strong." The two allies, he added, have no difficulty discussing their differences candidly, in an atmosphere of friendship.

"We share a fundamental commitment to wiping out terrorism and responding firmly to the threat posed by international terrorism," the spokesman said.

Whitehead's primary mission appears to involve repairing relations with Egyptian President Hosni Mubarak, who was furious at the U.S. interception of the Egyptian plane carrying the four Palestinian hijackers of the Achille Lauro, as well as Abbas and an aide.