Police searched today for the perpetrators of a bomb explosion that ripped through an Israeli specialty restaurant in West Berlin last night and injured 25 persons.

A statement by investigators said that the attack, which wrecked the Mifgash Israel restaurant in the city's central Wilmersdorf district, was probably politically motivated.

Following an early-morning search of three Berlin apartments, police detained six Palestinians but later released them. The six were suspected of belonging to the Popular Front for the Liberation of Palestine, a group that has been linked to two persons arrested Jan. 5 at Rome's Fiumicino Airport for possessing explosives.

The Berlin bureau of the Deutsche Presse-Agentur, the West German news agency, received two anonymous phone calls in connection with the explosion, one claiming a pro-Palestinian group was responsible, the other saying "a Dutch group" was involved. Both callers were described as having "foreign accents."

But the city's chief investigator, Manfred Kittlau, said that no concrete evidence had been found by this evening linking the bomb attack to the Palestinians and that the police were still considering all possibilities.

West Berlin, which was reported shocked by the attack, is home of a number of foreign political and religious groups.

According to a Bonn Interior Ministry report, West Germany in general has seen an increase of violent activity in recent months by foreign political groups and by extremist factions on both the left and right.

In a statement, the leader of West Berlin's Jewish community, Heinz Galinski, said that varied terrorist groups had for some time been united at least in their hatred against Israel and Jewish establishments. The bomb attack, he said, confirmed recent warnings about the clear strengthening of extremist circles on both the left and the right.

Eight of the 25 persons hurt in the explosion were still hospitalized this evening. One, a 14-month old baby, was reported in critical condition.

The restaurant owners, Dany Mezger and Naftali Schoenberg, both Israeli citizens, told Reuter news agency that they had not received any threats since opening the restaurant in 1968.