The Israeli government praised in enthusiastic terms today the Reagan administration's decision to intercept the Egyptian airliner carrying the Achille Lauro hijackers, but officials warned that it would be a grievous mistake for Italy to release the Palestinian guerrilla leader who accompanied the hijackers on the flight after negotiating their release.

Amid reports that Mohammed Abbas, head of one faction of the Palestine Liberation Front, might be released by Italian authorities, Israeli officials said Abbas should be held and brought to trial for murder along with the four hijackers because, the officials said, he had planned and ordered the terrorist operation that led to the hijacking Monday of the Italian liner off the port of Alexandria.

"He was in charge of the operation. He should be treated exactly like those who carried it out," a government official said. He said the fact that Abbas showed up at Port Said to help negotiate an end to the crisis should not exempt him from his responsibility in the hijacking.

Without offering substantiating evidence, Israeli officials have said that their intelligence has produced "absolute, complete and irrefutable proof" that Abbas ordered the four Palestinian guerrillas to board the Achille Lauro, and that Palestine Liberation Organization Chairman Yasser Arafat knew about the operation in advance.

The Israeli version of the incident is that the hijackers boarded the cruise ship intending to get off at the Israeli port of Ashdod to carry out a terrorist act in Israel but panicked when they thought they had been identified as the ship set sail from Alexandria for Port Said. Only then, according to Israeli officials, did the four gunmen decide to hijack the ship and hold the passengers hostage.

Israeli officials have continued to refuse to provide specific evidence to substantiate their assertions that Abbas directed the operation and that Arafat knew about it. They suggested that to do so would jeopardize intelligence sources.

One senior Foreign Ministry official, describing the Israeli intelligence data on the hijacking as "first class," said the government's assertions about Abbas and Arafat either would have to be accepted at face value or rejected, because the Mossad, Israel's external intelligence service, was not willing to disclose specific evidence.

But Israeli leaders were ebullient in their praise of the U.S. Navy's interception of the jetliner carrying the four hijackers.

Prime Minister Shimon Peres, in a telegram to President Reagan today, said Israelis "salute your courageous decision and decisive action."

Peres added, "We congratulate you and the U.S. Navy on the flawless implementation -- a major contribution to the international struggle against the double plague of cold-blooded murders and outright lies by both the perpetrators and their superiors. Your action is a landmark in the fight to eradicate terrorism and a shining example of your resolve."

Defense Minister Yitzhak Rabin, obliquely alluding to similarly spectacular steps by the Israeli armed forces against terrorism, said he welcomed "the joining of another country, a superpower, in the carrying out of an initiated action against terrorism."

Speaking on the Israeli Defense Forces radio, Rabin said, "I also believe that by intercepting the plane, they captured not only the terrorists themselves, but also all of the partners in the activities surrounding the attack, be they the head of this wing or the PLO representative."

The PLO representative he was referring to is Hani Hassan, a high-ranking Arafat aide who helped negotiate the surrender of the hijackers. But it was not confirmed that he was on the plane.

Foreign Minister Yitzhak Shamir suggested that the hijacking and its aftermath had given the Reagan administration a "better understanding" of the relationship between Egypt and the PLO.

Speaking at an airport press conference upon his return to Israel from an official visit to the United States, he said the Egyptian government's handling of the crisis had created in Washington an attitude of distrust and disaffection with both Egypt and the PLO.

He was referring to the Egyptians' decision to release the hijackers and give them safe passage to Tunis, the headquarters of the mainstream PLO Fatah branch and the PLF wing headed by Abbas.