Dressed uniformly in black, the protesters with Jewish Voice for Peace gathered on the pedestal shortly before 1 p.m. when they dropped massive banners with calls for a cease-fire and other slogans, such as “The Whole World Is Watching” and “Never Again for Anyone.” The group sang “Cease-fire now” and occupied the national monument for about 20 minutes before dispersing. The protest, which the group said included more than 500 people, continued on a ferry headed back to Manhattan.