Ayatollah Ruhollah Khomeini, the most prominent leader of the opposition against the shah of Iran, said yesterday from his place of exile near Paris that he will expel from his movement anyone who negotiates with the shah.

"The shah and his dynasty must go," Khomeini told a Paris-based station, Radio Luxembourg in a brief interview.

Khomeini hinted broadly that if the shah does not abdicate, he will give his followers orders to take up arms.

"Until now," he said, "I have not given my accord to start a civil war, but that could change."

Khomeini said that the shah's attempts to start a dialogue with his opposition comes "too late."

"We have told the representatives of the opposition like Mr. Ali Amini or Karin Sanjahi that if they accept negotiations with the shah, they will banned from our movement."

Amini met with the shah Tuesday and said the Sanjahi would meet with the shah shortly.

A spokesman for Khomeini insisted that the Moslem leader has systematically refused to meet with anyone he suspect might be carrying a message from the shah.

The spokesman said Khomeini has met with opposition leaders like Sanjabi at the country residence in Pontchartrain only as individuals, refusing to deal with them as party leaders. The spokesman said Khomeini also has always taken care to meet these people in the presence of witnesses.

This close aide of Khomeini described his attitude toward Sanjabi's National Front as basically uninterested. It claims to be the spiritual heir of the late Premier Mohammed Mossadegh, the Iranian national hero who nationalized Iran's oil and almost toppled the shah after World War II. The spokesman said the party was one of many tiny ones. He noted that Mossadegh himself had dissolved it, implying that it claims to represent his ideas are false.

There was a published report this week that Ardeshir Zahedi, the Iranian ambassador to Washington, had asked to see Khomeini and had been turned down. But the Khomeini spokesman said that Zahedi had never asked to see the religious leader and that he must have known in advance that any such request would be rejected.

Khomeini told Radio Luxembourg that a new Iranian constitution must be promulgated that "eliminates the clauses and the reforms brought by the shah and by his father."