Ban spoke a few hours after the UN Security Council called for an immediate and unconditional humanitarian ceasefire in Gaza during the Muslim Eid al-Fitr holiday marking the end of Ramadan.
"In the name of humanity, the violence must stop," Ban told reporters.
The UN chief said he had "long talks" with Israeli Prime Minister Benjamin Netanyahu on Monday, urging him to "stop the violence and to honor the international community's joint common effort and common call for a humanitarian ceasefire."
Ban has repeatedly called for a humanitarian truce over the past days, but he noted that "since Sunday a relative and very fragile calm on the ground has been established."
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The Israeli army said only one rocket had struck its territory since midnight, hitting the southern port city of Ashkelon, while in Gaza an AFP correspondent confirmed there had been no Israeli air strikes during the night.
Palestinian and Israeli leaders "have to show humanity as leaders" and stop the violence as a first step toward peace talks, he added, stressing that it was a "matter of their political will."
The United Nations is backing a bid by Egypt to broker a peace deal to end the latest flareup in the Gaza Strip that has left more than 1,000 Palestinians and 43 Israeli soldiers dead.
The death toll raises "serious issues of proportionality", said Ban. Israel and "all the parties" must do "vastly more" to protect civilians, he added.
Jordan has been circulating a draft resolution with such wording but diplomats do not expect the measure to come up for a vote in the near future.