In front of a crowd of supporters in southern Gaza after Friday prayers, al-Zahar said Hamas would be committed to a ceasefire if Israel abided by it.
Zahar said Hamas and other factions were committed to an agreement they had reached last year to stop rocket firing into Israel, although smaller groups continued to launch attacks.
"We are committed to self-restraint as long as there is no oppression and no aggression," said Zahar.
A spokesman for Israel's Foreign Ministry said Zahar's declared intentions will be tested by the reality on the ground. "Hamas has escalated the situation, it can now be de-escalated by simply stopping the rocket fire," said Yigal Palmor.
Meanwhile, Zahar insisted that the unofficial cease-fire is not a sign of weakness. He spoke to thousands of supporters after Friday prayers in the southern Gaza town of Khan Yunis.
Zahar also hinted that Hamas was using it to rearm and reorganize, and criticized rivals in the Palestinian Authority for new arrests of Hamas members in the West Bank.
Palestinians fired some 26 rockets and mortars into Israel this week, including one that exploded near a kindergarten. An IDF air strike wiped out a five-man rocket squad and a Palestinian shepherd was reportedly shot dead near the border.
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