The militant wing of Hamas has rejected the seven-hour humanitarian ceasefire declared by Israel.
"Israel's so-called humanitarian ceasefire is unilateral and it comes at a time when the Zionist enemy wants to distract the world from the massacres they have committed against our people in Gaza," Hamas spokesperson Sami Abu Zuhri told the television channel al-Aqsa.
"We don't trust their intentions and we ask our people to take extreme caution."
Israel had earlier announced that it would observe a unilateral temporary ceasefire from 10:00am local time (07:00GMT) to allow humanitarian efforts to take place.
Israel insisted there will be no fighting in the Gaza Strip region except in the southern city of Rafah where "clashes were still ongoing and there was Israeli military presence".
However the Israel Defense Forces (IDF) warned they would retaliate if attacked.
"We will continue to neutralise Hamas' tunnel network and will respond to any attempt to harm Israeli civilians or IDF soldiers," said IDF in a statement.
The latest announcement follows widespread criticism over the Israeli attack on a UN-run school in Gaza which killed at least 10 Palestinians. UN Secretary General Ban Ki-moon has described the attack on the international body's facility as a "moral outrage and a criminal act".
Islamic Jihad leader 'killed'
Meanwhile, an Israeli airstrike is believed to have killed a senior Islamic Jihad leader in the Gaza Strip. Danyal Mansour, the northern district commander of the militant group, was reportedly killed after his home in the Jabalya refugee camp was bombed. Six others were also killed in the attack.
The fighting between Israel and Hamas has entered its 28th day. At least 1,700 Palestinians have been killed, mostly civilians, including many women and children; Israel has lost 64 soldiers.