The Palestine Liberation Organization has tried to tell the United States that it has adopted a more moderate stance toward Middle East peace by removing members of the radical Rejection Front organization from its executive council, a PLO official said today.

But, according to diplomats and Palestinians interviewed here, the PLO signal has not yet been recognized by the United States.

The signal was the Palestinian National Council's approval last Monday of the makeup of the executive committee with no representatives on it of George Habash's Popular Front for the Liberation of Palestine, a group that opposes any Middle East peace settlement allowing for Israel's continued existence.

"That was the most significant political decision of the National Council meeting," said Sayd Hamami, the PLO's representative in London and a close associate of Palestinian leader Yassar Arafat.

Another PLO official said the National Council action was designed to show the world that the PLO had rid itself of its "hijacking, lunatic, Marxist-Leninist fringe."

"That's the Palestinians' message, the signal," the PLO official said.

The Palestinians had been asked by the United States and especially by Israel to give some tangible sign during their National Council meeting in Cairo that they had assumed the new, moderate approach displayed by such Arab nations and Syria, Egypt and Saudi Arabia.

U.S. Secretary of State Cyrus R. Vance, for example, called for the PLO to amend its national charter to recognize Israel's right to exist.

While falling to modify their charter, the Palestinians did pass a resolution that one PLO official said is aimed at erasing any doubt that all Israeli Jews and Palestinians can live together in peace.

In fact, according to PLO sources here, the mainstream Palestinians have accepted a two-state solution, with Israel continuing to exist and a new Palestine created on the West Bank of the Jordan River and in the Gaza Strip.

Hamami said the two states could live together in a form of detente as the United States and the Soviet Union now do.

He said that peace for Palestinians means an independent state and the recognition of the Palestinians' right to go back to all parts of Israel. Under the existing political realities, he said, he knows the Palestinians cannot return to Israel soon, but the recognition of their right to do so sometime in the future is necessary to keep their national identity alive.

"That means we speak for all Palestinians, not just for the West Bank residents," he said.

"I know more than you do that there is a Jewish state there," Hamami said. "Of course, we can't dismantle that state. I want it to disappear.I pray that it will disappear. But it will not."

That is one of the clearest statements made to date by a PLO official recognizing Israel's right to exist, and it was obviously aimed at a Western audience - especially U.S. diplomats.

Hamami is known as one of the most Westernized of the Palestinian officials. As head of the PLO's London office, his job is to present Palestinian policies in the direct terms the Western mind can understand rather than in the vaguer, more enigmatic manner favored by the Arabs.