UN High Commissioner for Human Rights Michelle Bachelet condemned Israel's actions, along with the rocket attacks on Israel by Islamist Hamas, which rules the Gaza Strip.
According to foreign media reports, the Israeli army tricked many Hamas fighters to retreat to the tunnels, after which jets bombed the network for about 40 minutes.
Civil unrest was meanwhile mounting between Israel's Arab and Jewish citizens, with protests and riots reported in communities in which a high proportion of Arab Israelis live.