"We will not allow the escalation on the fence to go unanswered," he said.
The Israeli military said it holds Gaza's Hamas rulers responsible for the attack and that it "will not tolerate" such incidents.
In a text message to reporters, Hamas spokesman Fawzi Barhoum threatened to respond.
"Targeting civilians is a dangerous escalation that cannot be tolerated. The resistance has the full right to respond to the Israeli crimes," he said.
Israel carried out a broad military offensive in Gaza nearly four years ago in response to years of near daily rocket fire. Major salvos from Gaza have subsided since then, but sporadic rocket fire has continued.
Gaza's Islamist Hamas rulers have largely refrained from rocket attacks since the devastating Israeli military offensive that killed hundreds of Palestinians.
Hamas, which has killed hundreds of Israelis in suicide bombings and other attacks, remains virulently anti-Israel in its rhetoric but has sought to keep things quiet as it consolidates control of Gaza, which it seized five years ago during a brief civil war against the rival Fatah movement.
Still, it is under pressure from smaller groups to prove that it remains in confrontation with the Jewish state.
The territory is home to numerous militant groups, including murky al-Qaida-inspired organizations that do not answer to Hamas. Gaza has also been flooded with weapons in recent years, many of them believed to have been smuggled from northern Africa and into Gaza through tunnels under the Egyptian border.