The Italian government vowed today to seek a peaceful solution to the hijacking of the cruise ship Achille Lauro but indicated it was not prepared to give in to terrorists' demands.

That position was underlined tonight by Defense Minister Giovanni Spadolini during a briefing for Parliament after a day of crisis meetings under Socialist Prime Minister Bettino Craxi.

"We count on reason prevailing and the solution should absolutely not be military," said Spadolini, "but we will not surrender to the terrorists." The statement came after the government mobilized diplomatically and militarily in the wake of the hijacking yesterday by Palestinians off the coast of Egypt.

Having placed the military on alert last night, Spadolini and Italy's military chiefs of staff today diverted naval vessels from maneuvers in the Ionian Sea to the eastern Mediterranean, sent a reconnaissance jet to chart the course of the Achille Lauro and airlifted four helicopters to Cyprus for possible military or rescue operations.

Craxi's almost nonstop meetings came amid signs that the act of piracy had seriously strained his five-party coalition and ultimately could bring the government down over the question of its policy toward Israel and the Palestinians.

Craxi and Foreign Minister Giulio Andreotti triggered a major political row here last week because of the vehemence of their reaction to the Israeli bombing of Yasser Arafat's Palestine Liberation Organization headquarters in Tunisia.

Both men denounced the Israeli raid in the strongest terms, equating it with the very terrorism that Israel said it sought stamp out. The sharpest criticism of their statements -- except for that from the Israeli government -- was by Defense Minister Spadolini.

Spadolini is a member of the small Republican Party, which has taken a strongly pro-Israel stance in contrast to that of Craxi, a Socialist, and Andreotti, a Christian Democrat.

Italy has stressed its strong stand against terrorism, especially since it broke the back of the Red Brigades terrorist movement. In the late l970s and early l980s, the Marxist group assassinated dozens of judges, policemen and politicians, including Aldo Moro, the president of the then governing Christian Democratic Party, and in 1981 kidnaped U.S. Gen. James L. Dozier of NATO's Italy-based southern command.

But Italy's traditional foreign policy of seeking close relations with the Arab governments across the Mediterranean has often brought criticism from Israel.

"We are working and we will continue to work so that everything may be resolved for the best," Craxi said after the day's meetings. "We are trying to avoid a tragedy."

Andreotti met with ambassadors of the United States, Israel and Syria, as well as a Catholic bishop once jailed by Israel for his support of Palestinians.

The Associated Press quoted Andreotti as saying that while initial reports indicated the hijackers were demanding 50 Palestinians held in Israel, later "demands seemed to aim at the liberation of Palestinian citizens arrested and detained in various countries, including Italy."

Spadolini said the military preparations were being made on a contingency basis only, because the government considered a military solution an "extreme action that we all hope to avoid."

After the Achille Lauro sailed within sight of the Syrian port of Tartus this afternoon, the Italian charge d'affaires in Damascus apparently considered going to the port in the hopes of making contact, but was ordered not to do so.

"We are lining ourselves with the American position, that is, not to negotiate with terrorists," the charge, Pietro Cordone, was quoted as saying.

This afternoon, the newspaper of Spadolini's party attacked the government's request last night for help from Arafat to end the hijacking.

While acknowledging that Arafat and his wing of the PLO had disavowed the hijacking, the newspaper editorialized that either he was being disingenuous and actually had a part in it or, if not, had no power to resolve the hijacking. Either way, the newspaper said, "it was unacceptable that the government asked the head of a terrorist organization for help and established almost a state-to-state relationship with it."

"Either way," the Republican paper said, "the terrorist attack on the Italian liner was the most crude refutation of a faulty policy."

The daily of Craxi's Socialists, Avanti, termed the Republican attacks "inadmissible on their merits" and "even more irresponsible and treacherous having been inspired by the minister -- responsible for defense -- at a time when the whole government is obliged to excercise, with the maximum efficiency in an emergency, its duty to save lives in danger."