VENICE -- The only thing that has been flowing more rapidly than the Reagan administration's cries of alarm about the Persian Gulf in recent weeks has been the supply of oil being shipped from that region.

Production and exports from gulf countries are up, prices are holding steady at $18 a barrel and OPEC is due to meet in two weeks to consider notching upward its 15.8 million barrel a day ceiling on total production.

When the gap between the rhetoric of alarm about oil supplies and their abundance in the market place gets this wide, it is time to start looking for a hidden agenda. The administration acts as if it has seized on a passing moment of tension to accomplish long-held goals that it cannot articulate openly.

My sense is that behind the smokescreen over Iran's Chinese Silkworm missiles lies a tangle of regional and global objectives that this administration will not be able to integrate into a successful policy in its twilight days.

More to the point, that is the sense of our most important allies, who were puzzled by the Reagan team's dramatic presentation of the stakes of the gulf conflict in public in the days before the Venice economic summit and that same team's diffident presentation of the issue in private here.

"It was pure Kabuki," said a senior European official as the summit closed, "all motion, with no clear message, much less a plan of action."

Three elements of the White House's true agenda seem clear. One is a campaign of coercive diplomacy aimed at getting Iran to stop attacking Iraq and to withdraw from Iraqi territory.

Laudable, the goal of ending the gulf war is also probably unattainable by this lame-duck administration. As they waited for Reagan to become president before freeing American hostages, the Iranians will wait for a stronger deal maker in Washington.

Secondly, the driving force behind the Silkworm campaign almost certainly comes from the Pentagon, which has long dreamed of getting basing rights at Dhahran in Saudi Arabia. A fleet of aerial refueling tankers positioned there would allow U.S. carrier-based fighters and attack planes to cover the gulf and the arc to Afghanistan that the Carter administration called the "Crescent of Crisis."

Saudi Arabia's royal family has always resisted this demand, fearing the political burden of an open military alliance with Israel's closest friend. Much of the recent banging of the war drum has been to bring the Saudis around on Dhahran. It will probably make them even more skittish about putting all their eggs in the U.S. basket in a time of crisis.

Finally, modest Soviet gains with Arab states have enabled Middle East experts in Washington to wrap their regional goals into a broader formulation about halting the Russian push into the Middle East.

Again, the result has been the opposite of what is intended. The administration's declarations on the gulf have underscored the reactive, me-too nature of its regional policy and the lack of sustainable independent American goals.

The administration in fact presents itself as being slow to apprehend that the oil trade has become suprisingly resilient in operating under war conditions.

While military frigates turn out to be tragically vulnerable to Exocets and other modern missiles, fully loaded and well compartmentalized supertankers are not. Crude oil packed into these tankers does not ignite easily, and casualties result almost entirely from direct hits on the crew's work area.

Moreover, significant changes are already occurring in the patterns of the Persian Gulf oil trade. Iraq last month exported 2 million barrels of oil a day via pipelines and trucks that bypass the gulf. Iraq plans a new giant pipeline that will free it from depending on gulf shipping for oil exports.

International Energy Agency figures show that OPEC produced 16.6 million barrels of oil a day in the second quarter of this year, 800,000 barrels more than the quota the cartel adopted in December.

The failure of these increases to depress the $18 a barrel price that has prevailed since December suggests two immediate conclusions:

1. OPEC's oil ministers can in their meeting on June 25 easily increase the production ceiling to 16.5 million barrels a day for the next six months.

2. There is an underlying stability in oil supplies that undermines Washington's outcries. The gap between rhetoric and reality should be narrowed as the basis for a policy that can command the support of the American public and America's Arab allies at the same time.