Secretary of State George P. Shultz said yesterday that he was "speaking for the American people" when he angrily told a news conference in Belgrade on Tuesday that the hijacking of the cruise ship Achille Lauro was a terrorist act and had no political justification.

Shultz created a stir in Belgrade when he pounded a table and publicly disputed Yugoslav Foreign Minister Raif Dizdarevic's statements that incidents like the Achille Lauro piracy must be viewed in the context of the Palestinian people's struggle against colonialism.

Shultz, who had been sharing the podium with Dizdarevic, immediately interrupted to say that the hijacking, in which Palestinian terrorists killed an elderly American and terrorized others, "is not justified by any cause that I know of."

Yesterday, while flying home after a 10-day European visit, Shultz said, "I just want people to see that in the United States we feel very strongly about this subject. I felt that by making an interjection at that point I was very much really speaking for the American people."

"I think that in the past year, we in the United States have seen the menace of terrorism more clearly. So support for doing something about it is stronger," added Shultz, who has been the most outspoken member of the administration in advocating a tough stance against terrorism.

He also insisted that there is no contradiction between his call Tuesday in Belgrade for giving terrorists "no place to hide" and the administration's reluctance to take measures against Iraq for harboring Mohammed Abbas, a Palestinian leader who allegedly masterminded the Achille Lauro piracy in October.

Shultz acknowledged to reporters Tuesday that Abbas, a member of the Palestine Liberation Organization executive committee, has been in Iraq and that the Iraqi government has refused U.S. requests for his arrest.

When he was asked yesterday whether Abbas is still in Iraq, the secretary replied, "I don't have any information otherwise." A State Department spokesman said yesterday that the United States would request Abbas' extradition if it is determined with certainty that he is in Iraq.

Although acknowledging that Iraq's apparent harboring of Abbas is "a problem," the secretary said, "I don't think we should feel that every time we identify a problem, we have to fire off a gun or break relations with someone. There are gradations."

Shultz again linked the PLO to terrorist acts in the Middle East.

He denied that his criticism of the PLO is at cross purposes with the efforts of Jordan's King Hussein to win PLO backing for a Jordanian-Palestinian delegation to enter peace talks with Israel. Shultz said the United States continues to back Hussein's search for those Palestinians who could play a role in the peace process.

However, the secretary added, "We have seen individuals who have associations with the PLO, including members of the executive committee, be associated with hostage-taking, acts of terror and murder. So you have to put that in the picture."