Hamas has described the resignation of Israeli Defence Minister Avigdor Lieberman as a "political victory for Gaza" amid threats to an uneasy ceasefire.

The Palestinian group's spokesman, Sami Abu Zuhri, said on Wednesday that Lieberman's resignation signalled a "recognition of defeat and failure to confront the Palestinian resistance", adding "Gaza's steadfastness sent a political shockwave" through Israel.

Lieberman said he was resigning in protest against an Egypt-brokered ceasefire reached with armed groups in Gaza.

The truce, announced on Tuesday by Hamas-led factions, was intended to end two days of Israeli aerial attacks on Gaza after a covert Israeli operation inside the strip, to which Palestinian factions responded with rocket fire.

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At least 15 Palestinians and two Israelis were killed in two days in the worst violence the strip has seen in two years.

Lieberman had advocated for a more decisive blow to Hamas and quit in protest.

Israeli Prime Minister Benjamin Netanyahu defended the truce saying the "leadership is doing the right thing".

Lieberman's resignation significantly weakens Netanyahu's coalition government and appears to bring about an early election.