In the gently sloping garden of the Franciscan Monastery in Northeast Washington, Mayor Walter E. Washington joined a procession of worshipers who were taking part yesterday in traditional Good Friday observances.

"I came to join the pilgrimage," the major said afterward. "I wanted the city to stop for a moment and reflect on the 14 stops of Jesus.

The District of Columbia's major was among thousands of Catholics and Protestants in the Washington area who marked Good Friday, the most somber day in the Christian calendar, at solemn church services yesterday. Good Friday commenmorates Christ's Crucifixion.

In processions resembling the one in which the mayoor participated, worshippers made the traditional 14 stations of the cross, a series of stops symbolizing Christ's joourney from Jerusalem to crucifixion on Mount Calvary.

Amid these Good Friday observances, Mayor Washington's visit to the stately, secluded grounds of the buff-colored Franciscan Monstery also appeared to carry social and political overtones.

The mayor, who has not yet announced whether he will seek reelection in this year's city campaign, acted very much like a candidate, shaking hands with worshipers and posing for photographs. "Just keep our faith in the Lord," he told one well-wisher.

The monastery, located at 1400 Quincy St. NE in the Brookland community, has been troubled during the past few months by a number of robberies, in which most of the victims have been elderly women. The mayor was accompanied by the city's police chief, Burtell M. Jefferson, at the Good Friday observances at the monastery to demonstrate the city's concern about the robberies.

Nonetheless, it was religion, rather than politics that dominated the occasion as the mayor, a Baptist, joined several hundred other, mainly Catholic worshipers beneath the tall evergreen in the Franciscan Monastery's hillside garden. "This is a day for all faiths," the mayor told one Franciscan friar.

He and Chief Jefferson walked in a slow procession led by a Franciscan friar dressed in traditional brown habit. The friar carried a brass Crucifix, drapped in a red cloth, an emblem of Good Friday. Beside the mayor walked the Rev. Matthew deBenedictis, superior of the monastery.

The worshipers paused for prayer near each of 14 statues marking "the way of the cross," as a priest, the Rev. Brian McTommony, intoned the meaning of each stop. The first was "Jesus is condemned to death"; the second, "Jesus takes up the cross," and the last, "Jesus is laid in the sepulchre." The mayor, in a gray suit carried a small prayer book and held his horn-rimmed glasses in his hands.

Mayor Washington had been invited to the Good Friday observance at the monastery by June Fowler, a frequent worshiper there. Mrs. Fowler said in an interview that she hoped the mayor's attendance would lead to increased police protection in the area. "For the last year or so, there have been quite a few muggings near the monastery," she said. "Old ladies have been robbed and knocked down."

A city police spokesman, Officer Gary W. Hankins, confirmed that 15 to 20 purse robberies had been reported within a few blocks of the monastery in the past six months and that several involved elderly complainants. One youth has been arrested, Hankins said, and other suspects are under investigation.

The incidents appear to have ended in the past month, and it was unclear yesterday whether the D.C. Police Department would increase patrolling of the area. "It isn't a situation where it's a widespread problem that hasn't been addressed," Jefferson said.

Nevertheless, participation by the mayor and chief in the Good Friday observances was viewed as a sign of reaccurance among some worshippers at the monastery.

"We'd like to have people come here and feel safe," said one friar, Brother Aloysius.