The United States and Iraq have yet to adopt new procedures for identification and communication between ships and aircraft in the Persian Gulf region, leaving vessels open to the same hazards that resulted in an accidental air attack on the USS Stark two weeks ago that killed 37 sailors, an administration official said yesterday.

But the hazards are greater now for Iraqi planes because U.S. ship commanders are more alert to potential dangers of approaching aircraft. Without an improved communications system, the official said, there is little to prevent "us from shooting down one of their planes" if it strays too close to a U.S. warship.

The two nations are attempting to negotiate an agreement that would establish new communications and identification procedures aimed at preventing another accidental attack, officials said. The leader of a U.S. military team investigating the incident told reporters in Baghdad late last week that the two nations had reached "preliminary agreement" on the procedures.

But the agreement has not been approved by either side, officials said. Administration officials said yesterday that U.S. ships still are relying on radar to illuminate approaching aircraft and that pilots and ship commanders have no new means of identification or communications.

Iraqi government officials told the U.S. team that the pilot who fired on the Stark never heard the two radio warnings transmitted by the ship's crew before the attack, even though Iraqi officials said he understood English and should have been monitoring the frequency used by the ship, according to congressional sources who have been briefed on the investigation.

The Iraqi government refused to allow the U.S. investigative team to talk to the pilot, according to congressional sources.

Iraqi officials told the team that the pilot had made 15 successful missile attacks on tankers flying an Mirage F1 fighter. But they said he was not accustomed to flying the Mirage with two Exocet missiles. The planes traditionally have been equipped to carry only one missile, they said. The plane was recorded on U.S. radar as flying an erratic path along the Saudi Arabian coast.

In a related development, a State Department spokesman said that over the weekend the United States had sent a message to the leaders of Western nations as well as to U.S. allies in the gulf asking in general terms for help in protecting international shipping there.

"We're saying that maybe there is something more they can do," the spokesman said.

He said what help European nations might be able to provide would be discussed at next week's Venice summit. The administration will ask Arab gulf allies "fairly soon" for such things as landing rights for U.S. aircraft, he said.

The decision to send the messages apparently was a reaction to congressional assertions that the United States should not act alone in seeking to protect international shipping in the gulf and that Western and Arab countries with a direct interest there should also help.

At a White House ceremony yesterday marking the 40th anniversary of the post-World War II Marshall Plan, President Reagan reminded West European nations that it was as much in their interest as that of the United States to help safeguard the flow of oil from the gulf.

Meanwhile, the Reagan administration announced yesterday that it intends to sell Saudi Arabia 1,600 Maverick air-to-ground missiles in a $360 million arms deal. There was an immediate outcry in Congress because of Saudi reluctance to help U.S. military forces in the Persian Gulf.

State Department spokesman Charles E. Redman said the administration had notified Congress Friday of its decision to provide the Saudi kingdom with the latest AGM65D model of the Maverick in place of 1,600 B-model missiles Congress approved in 1984 but were never delivered.

The D-model uses an infrared guidance system, while the earlier AGM65B, no longer in production, used a television system. The Saudi have bought 2,500 A- and B-model Maverick missiles since 1976.

A spokesman for the American-Israel Public Affairs Committee (AIPAC) said the organization plans to oppose the sale "really actively" and will seek a congressional resolution disapproving of the sale. More than 30 senators and representatives already have signed a letter to President Reagan expressing disapproval of a possible sale of 12 to 15 additional F15 fighters to Saudi Arabia.

Rep. Lawrence J. Smith (D-Fla.), a member of the House Foreign Affairs Europe and the Middle East subcommittee, charged that the Maverick sale was simply "a payback" for the $32 million in Saudi contributions to the U.S.-backed Nicaragua contras and had no "strategic justification."

He said he would introduce a resolution of disapproval of the sale in the House today and predicted it would gain support of the two-thirds of members that would be needed to override a possible presidential veto.