Israel has threatened to bar the entry of fuel and humanitarian aid into Gaza until Hamas releases all captives.
"Humanitarian aid to Gaza? No electric switch will be turned on, no water tap will be opened and no fuel truck will enter until the Israeli abductees are returned home," Israeli Energy Minister Israel Katz said in a statement.
The Israeli military's withering air campaign on Gaza has killed 1,417 people and wounded over 6,000 others. It said it was preparing for a ground assault in the enclave, but that Israel's political leaders had not yet taken a decision.
Israel announced an 'emergency government' on Wednesday which will be focused entirely on the war with Hamas.
At least 1,300 people in Israel have also been killed and thousands more wounded.
Hamas Thursday morning said they fired a barrage of rockets at Tel Aviv in response to the Israeli air strikes that targeted "civilians" in two Gaza refugee camps, killing at least 15 people, the Palestinian group said.
Palestinian residents said did not receive any warning from Israeli security before their homes were bombed.
Israeli soldiers mobilised along the Lebanese border after a false alert Wednesday evening, where there were reports of a possible infiltration.