The truce will take place between 0700 GMT (1230 IST) and 1400 GMT (1930 IST) today and will only apply to parts of the Gaza strip where there is currently no military activity.
The unilateral limited truce came after an Israeli attack yesterday on a UN-run school sheltering about 3,000 displaced Palestinians that killed 10 people and wounded 30 others.
It was the third deadly attack by Israeli military on a UN school sheltering Palestinians during the conflict that started on July 8. UN chief Ban Ki-moon strongly condemned the attack, terming it as a "moral outrage and a criminal act" and demanding that those responsible for the act should be held accountable.
In a statement, he said: "This madness must stop." The US, a close ally of Israel, also denounced the attack and declared it as "disgraceful". "The coordinates of the school, like all UN facilities in Gaza, have been repeatedly communicated to the Israel Defense Forces," State Department spokeswoman Jen Psaki said.
"We once again stress that Israel must do more to meet its own standards and avoid civilian casualties," Psaki said. The Palestinian militant groups received the truce with distrust, with Hamas asking people in Gaza to be wary.
"We don't trust their intentions and we ask our people to take extreme caution," a Hamas spokesman said, accusing Israel of attempting to "distract the world from the massacres they have committed against our people in Gaza."
Israeli strikes on Gaza early today killed 11 people, including an Islamic Jihad commander, raising the Palestinian death toll to over 1,820, according to Gaza health officials.
More than 9,320 people have been wounded in the 27-day conflict. The dead include 398 children, 207 women and 74 elderly people. On Israeli side, 64 soldiers have been killed. Two civilians and a Thai worker in Israel have also died.