MANILA, Philippines (AP) _ Unknown assailants hurled a grenade at the walled home of Cardinal Jaime L. Sin on Thursday, a day after the archbishop of Manila spoke out against urban violence. Sin was not hurt and police said two passersby were slightly injured.

Patrolman Benito Angeles said the grenade exploded about 6 p.m. at the cardinal's residence in suburban Mandaluyong. He said the attackers fled in a white car.

Sin, the leading Roman Catholic prelate in the Philippines, was in his bedroom at the time, said his spokesman, Felix Bautista.

Bautista said the cardinal had no immediate comment. A spokesman at Malacanang Palace said President Corazon Aquino had been told of the attack, but also had no comment.

The grenade bounced off the high, white wall and exploded at the edge of the sidewalk, about 60 yards from Sin's guarded residence.

Shrapnel from the grenade, which police said appeared to be a type issued to combat troops, dug at least three to four dozen small holes in the concrete wall and the curb.

Lorenzo Aquran, 47, received shrapnel wounds in his right shoulder. He told reporters he was walking along the sidewalk to his nearby home when he saw a man toss a grenade from a car.

''I turned and ran but not fast enough,'' said Aquran, a local ward leader. A woman, whose name was unavailable, was taken to a neighborhood hospital.

It was the second explosion in the Manila area in 24 hours. A bomb exploded shortly before midnight Wednesday outside the town hall in suburban Caloocan City, shattering windows but causing no injuries.

On Wednesday, Cardinal Sin decried the growing urban violence and appealed for ''peace in our troubled land.''

''I have observed that there are continuous killings and terrorism among our cities and municipalities,'' he told a news conference. ''These sad incidents must be stopped.''

The cardinal's appeal followed a series of attacks on lawmen in the Manila area, most of which authorities blame on Communist rebels. Two former guerrillas - Bernabe Buscayno and Conrado Balweg - were targets of assassination attempts this month.

The attempt on Buscayno has been blamed on rightists. Communist rebels are believed behind Sunday's ambush of Balweg's convoy in northern Luzon. He was unharmed but eight companions were killed.

Cardinal Sin has strongly urged priests and nuns to avoid politics and the rebels.

But he openly supported some pro-government candidates in last month's congressional elections, and was criticized by opposition conservatives because of it. He also called on Christians not to vote for leftist candidates.

Cardinal Sin played a key role in the February 1986 ouster of President Ferdinand E. Marcos. He urged people to take to the streets to protect military officers who rebelled against Marcos, triggering the ''people power'' revolt that forced the 20-year leader from power.

On April 28, unknown assailants tossed a grenade at the home of Bishop Antonio Fortich in Bacolod, about 300 miles south of Manila. It landed a few yards from his bedroom, breaking windows but causing no injuries.

A group calling itself Christians Against Communism claimed responsibility for the attack on Fortich, who has demanded land reform and reconciliation with rebels on impoverished Negros island.