Hamas on Tuesday rejected a truce proposed by Egypt.
The number of dead in the conflict in Gaza has reached 203, with 1,520 injured, the Health Ministry spokesman Ashraf al-Qedra said on Wednesday.
The cross-border attacks continued with rockets from militants in the Gaza Strip and airstrikes from the Israeli military.
Hamas and Palestinian armed groups on Tuesday rejected a truce proposed by Egypt, prompting Israel to warn that it would intensify a deadly offensive aimed at curbing rocket attacks.
Israeli warplanes bombed targets throughout the Gaza Strip about every 10 minutes, killing at least 10 Palestinians since the strikes resumed late on Tuesday.
The bombed targets included what Israel said were groups of militants firing rockets and houses of militants and Hamas leaders, including, witnesses said, that of former foreign affairs minister Mahmoud al-Zahar.
Late on Tuesday, Israel had its first fatality of the Gaza conflict – a 38-year-old civilian killed by shrapnel from a rocket at the Erez crossing on the northern Gaza border.
Hamas, the Islamist movement in de facto control of the Gaza Strip, and the smaller Islamic Jihad, announced that they would not accept the truce put forward by Egypt.
They rejected the truce in spite of the pleas by U.S. Secretary of State -John Kerry, German Foreign Minister Frank-Walter Steinmeier and other members of the international community.
Both groups said they felt sidelined by Cairo. Hamas’ armed wing, the Qassam Brigades, complained its fighters had not been consulted.
Hamas, Islamic Jihad and other armed groups launched 142 rockets at Israel since the truce failed, with air raid sirens howling across the country.
Israeli Prime Minister, Benjamin Netanyahu, warned late Tuesday Hamas would “pay a heavy price” for rejecting the ceasefire.
The Israeli army overnight called on Palestinians in northern Gaza to leave their homes “for their own safety”.
The government has authorised the army to mobilise 40,000 reservists and, since last week, has had three brigades on the Gaza border.