The militant leader in a recording posted on the internet on Monday also called on Muslims in Yemen, Afghanistan and Somalia to press ahead with fighting "crusaders" – a term used to denote the West – and their agents.
"Israel's Arab aides are trying to impose a calm (truce) on the people of Gaza to stop their jihad ... I tell our brothers and folk in Gaza that jihad to liberate Palestine and all Islamic land should not stop," Ayman al-Zawahri said.
Egypt has been negotiating a truce between Hamas, which controls Gaza, and Israel following an Israeli offensive late in December in the coastal strip to punish Hamas for firing rockets at Israeli towns. About 1,300 Palestinians were killed.
"I reaffirm to our brothers the fighters in Gaza and everywhere that the mujahideen against crusaders in various battle zones are willing to give their brothers in Gaza and everywhere training and preparation," said Zawahri.
Without naming Hamas, which al-Qaeda has often criticized for dropping suicide bombings to play a political role, Zawahri advised the Islamist group against blending with non-Islamist factions under the umbrella of the Palestine Liberation Organization, led by Palestinian President Mahmoud Abbas.
'Talk of fixing PLO is futile'
Abbas' Fatah movement is the largest of 11 groups that constitute the PLO, which in the early 1990s signed peace accords with Israel that aim to establish a Palestinian state.
"Talk of fixing the Palestine Liberation Organization (PLO) is futile," said Zawahri. "The PLO is a secular entity that does not uphold Islamic law and it is the entity that dropped jihad from its covenant."
Hamas has said Egypt will host reconciliation talks between Palestinian factions on Wednesday
The Egyptian militant leader also urged Somalis not to fall for a "secular constitution" and said militants there will not drop their weapons and fight the "US-made government".
Somalia's new President Sheikh Sharif Ahmed earlier this month selected the Western-educated son of a murdered former leader to be prime minister in a power-sharing government intended to end civil conflict in the Horn of Africa nation.
Zawahri praised what he described as an "increasing jihadist awakening in the Arabian Peninsula" and called on Yemeni tribes to follow the example of Afghan tribes in fighting US influence in the central Asian country.
In his recording Zawahri also urged Afghans to rally around the Taliban militant, al Qaeda's key ally in Afghanistan, to drive away US-led forces.