Nearly 1,000 changing, sign-bearing pro-Castro Cubans demonstrated last night outside the United Nations and the United States Mission to the United Nations and in the Times Square area.
        Heavy police details had kept the crowds behind barriers most of the day and no violence erupted until a smaller group of pro-Castro Cubans blocked pedestrian traffic in Times Square. The police made two arrests and two policemen were injured during a brief scuffle with demonstrators.
        Many of the demonstrators carried Cuban flags and pictures of Dr. Castro as they marched from the United Nations Plaza along Forty-second Street to the corner of Eight Avenue and Forty-third Street.
        An emergency police signal brought ten radio cars and ten mounted policemen to that area. The crowd then broke up into four factions and departed in different directions.
        A few minutes later, at 8 P.M., a smaller group of demonstrators formed on the sidewalk on Broadway between Forty-second and Forty-third Streets to cheer and boo the sign bulletins revolving around the building in Times Square.
        They shouted, "Yellow press," "Hands off Cuba" and "Yankee no, Cuba si."
        At this point ten mounted policemen arrived, drove their horses on the sidewalk, dispersed the crowd and made two arrests. The demonstrators shouted angry epithets at the police, but then dispersed.
        The demonstrations began at the United Nations and the United States Mission at 2 Park Avenue about 5 P.M. Each group numbered about 500.
        An hour later, the group demonstrating at the mission offices marched to the United Nations Plaza and was assigned to a separate picketing area. In general, the demonstration was noisy but orderly.
        Many carried placards bearing such hand-written inscriptions as "End U.S. intervention in Cuba," "Hands off Cuba," "Socialism si, Imperialism no," and "Cuba si, Yankee no."
        Shortly after 7 P.M. the two groups left the United Nations Plaza and were allowed to march west along Forty-second Street on both sidewalks.
        The police, including about twenty-five mounted patrolmen, held back traffic at the lights but restrained the demonstrators from crossing from one side of the street to the other.
        Pedestrians along the route paid little attention to the marchers. The parade was orderly until it reached Eighth Avenue.
        When the police dispersed the crowds there, it appeared that the demonstration was over, but a few minutes later the smaller, disorderly group appeared in Times Square.