The detainees were said to be 19-year-old Abed Husni Matariyya, 32-year-old Rami Abdul-Hayy Matariyya, and 34-year-old Muhammad Abdul-Hayy Matariyya, eyewitness Jamal Matariyya told Ma'an.
No Israeli spokesperson was available for comment.
Settler violence in Hebron is commonplace. Around 700 Israeli settlers live protected by the army amongst 30,000 Palestinians in the old city area.
Palestinians frequently complain that the Israeli army does nothing to prevent settler attacks, even when directly witnessing an incident.
Separately, Israeli forces prevented more than 60 farmers and international solidarity activists from working on a land reclamation project in the village of Beit Ummar, north of Hebron.
Spokesman for the popular committee against the separation wall in the village Muhammad Ayyad Awad said farmers and solidarity activists wanted to help Hussein Muheisin Awad reclaim part of his land but a settler fired gunshots into the air to scare them.
Israeli forces then arrived and expelled the volunteers, Awad said.