Nowhere in Art 51 of Charter is self-defence limited to states. The 2006 ICJ opinion accepted Israel's right of self defence were there is a grave and imminent peril - see par 140. Also opinion was dealing with the Wall which is fundamentally different issue to current crisis. Also, partiality of ICJ panel was questionable.
Woman moderately wounded by firebomb thrown at her car in north J'lem (Haaretz)
from the article: Israel's right to self-defense against Hamas