An Israeli penchant for practical jokes backfired on an unidentified Army intelligence operative here today when his April Fool's Day report of an assassination attempt against Lebanese Moslem leader Nabih Berri duped both Israel's defense minister and its state-run radio.

The perpetrator reportedly faces prosecution after an embarrassed Defense Minister Yitzhak Rabin, who had interrupted a session of a parliamentary committee to announce the supposed attack, had to admit to the lawmakers a few minutes later that he had been the victim of a bad joke.

The false intelligence report also found its way to Israel Radio, which broadcast it on two successive hourly newscasts before retracting the item.

Israel radio based its report on a call from Micky Gurdus, who monitors foreign radio broadcasts for the station. Gurdus, in turn, said he was tipped by Rabin's spokesman, Eitan Haber.

"It never dawned on me that it would be an April Fool's joke," an upset Gurdus said later.

Haber conceded that he had called Gurdus to verify after receiving the same intelligence report that Rabin got. Haber said the intelligence report cited broadcasts over two Lebanese radio stations -- Voice of the Nation and Voice of the Arab Revolution.

In Lebanon, spokesmen for Berri and for Voice of the Nation radio condemned Israel for what they called a sick joke.

Israel radio reported tonight that the unidentified jokester "is to be charged and may be imprisoned."

"I don't think it's funny," the radio's editor-in-chief, Osnat Lander, told reporters. However, there was a certain poetic justice in the station's having been hoodwinked.

On its popular 7 a.m. newscast, the state radio reported that Swiss authorities in Geneva had agreed to give the Israeli government information on Swiss bank accounts held by Israeli citizens. So many panicky listeners called that the radio did not even wait until the end of the newscast to admit that the story had been an April Fool's joke.