Israeli police early this month arrested several Palestinians from the occupied Gaza Strip who said they planned to attack the U.S. Embassy in Tel Aviv with a hand grenade, Haim Bar-Lev, the country's minister of police, said tonight.

In a telephone interview, Bar-Lev confirmed reports that security agencies here had thwarted a plot to attack the embassy, but he suggested that it should not be viewed in the same light as the two attacks that destroyed U.S. Embassy facilities in Beirut or one that caused major damage and injuries at the embassy in Kuwait.

"This was a very unsophisticated group of people who had a hand grenade and were looking for an object," he said. "Among the things they mentioned was the U.S. Embassy. By no means was this a planned operation aimed at your embassy. They were people with one hand grenade who were looking for a target."

Bar-Lev said that about five Palestinian young men from the Gaza Strip were involved, and that they also mentioned "schools and buses" as potential targets. He said they were arrested about three weeks ago in the Tel Aviv area, where thousands of Gaza Strip residents commute daily to jobs in Israel.

Bar-Lev said the men are still in custody and are being questioned as the investigation continues.

U.S. sources said they agreed in general with Bar-Lev's characterization of the seriousness of the incident.

Although the apparent plot to attack the embassy in Tel Aviv was not on the same scale as the suicide truck bomb assaults on American embassy facilities in Beirut, the incident seemed certain to increase concern about the safety of U.S. diplomatic missions throughout the Middle East.

The embassy attacks in Beirut and the destruction last year of the U.S. Marine headquarters there have led to tighter security measures for U.S. diplomatic missions around the world, and particularly in the Middle East. At one point earlier this year, a large truck was parked outside the entrance to the embassy in Tel Aviv for the obvious purpose of blocking the route of car bomb drivers.

However, the embassy, on a narrow but heavily traveled street that runs north from downtown Tel Aviv near the coast, is in a difficult area to protect. The two U.S. Consulate facilities in Jerusalem -- one in Jewish West Jerusalem and the other in Arab East Jerusalem -- also are on busy thoroughfares where passing traffic is not routinely controlled. The East Jerusalem consulate recently underwent a major revision of its security facilities.

While upgrading security provisions at their facilities here, U.S. officials clearly count on the ability of Israeli security agencies to detect and prevent planned attacks to provide them with an added measure of protection that has not been available to U.S. diplomats in Beirut.

In the telephone interview, Bar-Lev confirmed that U.S. officials here were not immediately notified of the arrest of the Palestinians who allegedly said they planned to attack the embassy. He said U.S. Ambassador Samuel W. Lewis later mentioned this to him and said that the embassy would like to be informed immediately of such incidents even when they are not considered serious by Israeli authorities.

"But in this case there was no reason to alarm them," Bar-Lev said in defense of the delay in notifying Lewis and his staff.

State Department spokesman John Hughes said in Washington that "there is no suggestion there was any lag in informing the United States." He would not say when the United States was informed of the attempt but said, "We received the information in a timely fashion." The entire incident, Hughes said, "points up the competence of the government of Israel for the protection of foreign government facilities."

While hand-grenade attacks are not common in Israel, Bar-Lev noted that in Tel Aviv on Monday a hand grenade was hurled at a city bus, injuring several people.

Asked why Israeli military censors initially prevented reporting of the incident, which still has not been mentioned in Israeli newspapers or broadcasts, Bar-Lev said, "This was not a police action that prevented a big catastrophe, so there was no reason to make a big fuss about it."