A member of Islamic Jihad said its men attacked Morag settlement and that one had been wounded and admitted to a Palestinian hospital. Islamic Jihad had no immediate word on fatalities.
Violence in occupied Gaza and the West Bank has largely subsided since Palestinian President Mahmoud Abbas and Israeli Prime Minister Ariel Sharon declared a ceasefire in February.
But truce violations have continued, with Israel conducting air raids and Islamic Jihad carrying out several attacks.
The violence has raised fears that Israel's planned Gaza pullout could be disrupted and has dampened hopes of peace talks afterwards.