ROME, JUNE 4 -- On the eve of the Venice summit meeting, where President Reagan is expected to seek European support for his plan to provide naval protection for shipping in the volatile Persian Gulf, a senior Iranian emissary is touring European capitals this week to ask their opposition to the move.

"Iran is opposed to any foreign military presence because it believes that such a presence not only fails to guarantee security in the Persian Gulf but it in fact constitutes a dangerous element in increasing tensions there," Iranian Deputy Foreign Minister Javad Lariajani said here today after meeting yesterday with Italian Foreign Minister Giulio Andreotti.

According to Mohammed Hassan Ghadiri, an Iranian Foreign Ministry spokesman, Lariajani is in Europe to present Iran's views on the gulf and to try to convince Europeans that their own best interest lies in opposing U.S. plans to provide military escorts to convoys headed for Kuwait, the gulf sheikdom whose ships have been targets of Iranian attacks.

The upgraded U.S. naval involvement in the gulf, Ghadiri argued, was the result of the "internal problems President Reagan is having because of the Irangate affair," which he proclaimed "a great Iranian victory" over Washington.

Reagan, he said, was acting even against the United States' own national interest to safeguard "his own personal interests and those of his staff," and Europe, Ghadiri said, should not be fooled into thinking that following the U.S. lead in the gulf served any European interests.

A week ago, Defense Secretary Caspar W. Weinberger, in a meeting of defense ministers of the North Atlantic Treaty Organization, suggested that NATO members, collectively or individually, should provide support to the upgraded U.S. naval presence in the gulf. The suggestion has gotten a cool reception in European capitals.

After meeting with Lariajani yesterday, Andreotti, in fact, took up Iran's argument, declaring that "the less military presences in the gulf, the better it is for all." The Iranians said Andreotti agreed that any military step-up in the gulf endangered security.

Ghadiri today reiterated Iranian warnings against U.S. military intervention in the gulf, but did not say what Iran intended to do about it.

"The Persian Gulf is a sea deep enough for U.S. ships to be sucked to the bottom," Ghadiri said, in cryptic response to questions about whether Iran would attack U.S. vessels. Asked what that meant exactly, he said: "Just like Tabas."

It was near Tabas, Iran, that the 1980 U.S. commando mission to free the American Embassy hostages in Tehran foundered, killing eight U.S. servicemen in a collision between aircraft.

The United States agreed last week to put 11 of Kuwait's 22 oil tankers under U.S. flag and to provide them with a naval escort in the war zone. A month ago the Soviet Union leased three of its tankers to Kuwait to lend them the protection of the Soviet flag.

Lariajani, who visited Bonn before coming here, said the solution to the gulf problem is not sending in foreign fleets but to persuade Iraq to quit attacking Iranian ships.

Before leaving today for talks in Brussels, the capital of the European Community, Lariajani said that "if there is no security for the Islamic Republic of Iran, then there will be no security for any other country, especially those that border the gulf."