PARIS, JULY 20 -- France, locked in a tense confrontation with Iran, has warned commercial ships flying the French flag to stay out of the Persian Gulf region, it was reported today.

The warning, from the government's Sea Secretariat, apparently reflected fears that Iranian gunboats could attack French shipping in an extension of the three-week-old standoff between Paris and Tehran over French demands that an Iranian official here be made available for questioning about terrorist bombings.

The two governments broke diplomatic relations on Friday. The action ended France's 15-month effort to cultivate better relations with Iran.

The French government's advice to French ships, reported by the national news service Agence France-Presse, came as the United States prepared to provide U.S. naval and air escorts for Kuwaiti oil tankers plying the gulf under U.S. flags acquired in recent changes of registry.

The issue that led to the French-Iranian diplomatic break was the French government's insistence that the Iranian official wanted for questioning, Wahid Gordji, leave the Iranian Embassy, where he has been hiding for six weeks, to respond to a summons from a French judge investigating last fall's wave of terrorist bombings.

Foreign Minister Jean-Bernard Raimond said last night that this point is not negotiable. But the Islamic government in Tehran has refused to produce Gordji, and Iranian President Ali Khamenei was quoted today as saying, "We will not retreat even one step."

French police have surrounded the Iranian Embassy here since June 30 to prevent Gordji's escape. In addition, France has prevented the embassy staff of five diplomats and about 40 other officials from leaving France until the crisis is resolved.

This step was taken to protect French diplomats and other officials in Tehran. Iranian authorities, who have ordered the French Embassy surrounded by Revolutionary Guards, last week charged French consul Jean-Paul Torri with espionage and drug trafficking. Officials here said called this an attempt to create a parallel with the Gordji case.

The French Foreign Ministry has insisted that Gordji, who has only an official passport, is not covered by diplomatic immunity and must submit to French jurisdiction. Torri, the ministry said, is an accredited diplomat and thus must be allowed to leave Iran under the Vienna Convention on diplomatic practice.

Four Iranian officials left the embassy today under police escort for a brief visit to the Iranian Melli Bank and the Iran Air offices, which was taken as an indication that preparations for the departure of the Iranians were being made.

{In Washington, White House spokesman Marlin Fitzwater backed France in the Embassy dispute, saying that the French action was justifiable and that "we are supportive of France." State Department spokeswoman Phyllis Oakley criticized Iran for making threats against French diplomats in Tehran. Oakley added, "The United States regards the use of a diplomatic mission to shield a citizen who does not enjoy diplomatic immunity from legitimate legal inquiry as a perversion of international diplomatic practice."}