Gunmen kidnapped an Irish officer serving with the U.N. peacekeeping force in southern Lebanon Thursday, police sources said. The police sources said the kidnapping occurred in the village of Tibnin inside Israel's self-established security zone in southern Lebanon, nine miles north of the Israel-Lebanon border. Police said the gunmen were carrying automatic weapons when they kidnapped the Irish officer, who was part of the U.N. Interim Force in Lebanon. UNIFIL members have been harassed frequently in the past by Moslem guerrillas because the peacekeepers hamper their efforts to fight Israel across the border.