The Reagan administration yesterday ordered the Palestine Liberation Organization's Washington information office closed within 30 days, State Department spokesman Charles E. Redman announced.

"This action is being taken to demonstrate the United States' concern over terrorism conducted and supported by organizations affiliated with the PLO," Redman said.

He said the Justice Department had advised that the First Amendment to the U.S. Constitution, which protects freedom of speech, did not prohibit ordering the office closed.

He said no hearings had been held before the closure. No one was being expelled and the PLO's observer mission in New York would remain open.

Before the move was confirmed, Rep. Jack Kemp (R.-N.Y.), who is sponsoring legislation in Congress to close the office, issued a statement saying the closure was a "strong signal to the rest of the world that America's war on terrorism is being waged strongly."

But the move was immediately condemned by Arab groups who argued that it would damage the peace process in the Middle East.

James Zogby, director of the Arab-American Institute, said it was a "cowardly election year stunt" designed to lock in an "anti-Palestinian perspective."

A spokesman for the American Civil Liberties Union called it a violation of free speech and said the ACLU would consider legal action if the PLO wished to go to court.

The closure ends months of debate in the Reagan administration about the future of the PLO office and preempts congressional attempts to close it.

The United States supports the "legitimate rights" of Palestinians and believes "it is important for Palestinian representatives to participate in all stages of the peace process," Redman said.