"You will soon find out that Gaza is the wrath of God," he said.
Meshaal's warning came as Israeli soldiers, tanks and armoured personnel carriers massed along Gaza's border, preparing for what many speculated could be a ground offensive.
Medical officials say at least 437 people have died in Gaza and 2,250 have been injured since Israel's aerial bombardment began last week.
Four Israelis have been killed in the same period by Palestinian rockets, including longer-range weapons that have hit the port of Ashdod and the desert town of Beer-sheva.
On Saturday, Israel's military said more than a dozen rockets have been fired over the border.
Palestinians also reported more Israeli air strikes across the Gaza Strip. A school was among the buildings bombed by the Israelis.
Israeli jets have fired more than 700 missiles into Gaza since the assault began last week.
Ayman Mohyeldin, Al Jazeera's correspondent in Gaza, said: "The Israeli military continues to pound targets everywhere in the territory. On the eighth days of attacks people here are very much terrorised by what is going on.
"The Israeli military is engaging in very aggresive psychological warfare. They have been dropping leaflets warning Palestinians that they have to flee their homes and warning that anyone who lives in area that could be a possible target that their home will be targeted as well.
"So that is causing a ripple effect of fear, but the question is where do 1.5 million Palestinians trapped in Gaza go".
Trucks carrying more than 200 tonnes of Syrian Red Crescent aid left Kura Al Assad for Gaza on Saturday as concerns for a looming humanitarian disaster grew.
Israel says that there is a humanitarian crisis in Gaza and that it has increased its shipments of goods into the territory.
Speaking to Al Jazeera, Azmi Bishara, an Israeli-Palestinian and former Knesset member, said: "Mostly, the war against such a place – slums and refugee camps - can only be a war crime.
"Whatever the military result, the political situation would be the same. What is called in American language the axis of moderation, or the moderates in the Arab world, have already had a blow, they are weaker than before.
"I think this is the only practical 'achievement' of the war that the people who are for the settlements in the region are less legitimate now and weaker than they were before the war.
Meshaal, speaking from the Syrian capital of Damascus on Friday, said Palestinians in Gaza were ready for any land offensive made by the Israelis.
"This battle was imposed on us and we are confident we will achieve victory because we have made our preparations.
"Our position is clear. We will not give in. Our resolve cannot be broken," he said.
"Our demand is also clear. The war must end, the siege lifted, and crossing points open without restriction."
|Meshaal says Hamas is prepared to handle an Israeli ground offensive [AFP]
But George Bush, the US president, in his first public comments on the hostilities, said Hamas had "instigated" Israel's war on Gaza, referring to the rocket attacks on Israel's southern towns.
"There must be monitoring mechanisms in place to help ensure that smuggling of weapons to terrorist groups in Gaza comes to an end," he said in remarks prepared for his weekly Saturday radio address.
Osama Hamdan, a senior Hamas official in Beirut, told Al Jazeera that the party to be blamed for the present situation is Israel, not Hamas.
"It's clear now that Israelis are blocking all the political solutions. The main question is supposed to be what will be the right end for this? And the clear answer is ending the occupation."
Speaking to Al Jazeera, Nir Rosen, a Beirut-based journalist, said: "There isn't very much [Hamas] can do except resist and withstand the Israeli assaults.
"These attacks are described as an Israeli retaliation which is ridiculous. Every Palestinian act of resistance is a retaliation for 60 years of occupation and dispossession.
"This use of violence is essential to Zionism, in an attempt to crush the Palestinian spirit to crush the Palestinian resolve."
Nicolas Sarkozy, the French president, begins a two-day four-nation tour of the Middle East on Monday, hoping to rally key players behind an initiative for a ceasefire in Gaza.
Sarkozy will visit Egypt and Syria before travelling to Jerusalem on Monday for talks with Ehud Olmert, the Israeli prime minister, and to the West Bank to show support for Mahmoud Abbas, the Palestinian president.
Abbas and several Arab foreign ministers are flying to New York over the weekend to urge the UN Security Council to adopt an Arab draft resolution that would condemn Israel and demand a halt to its bombing campaign in Gaza.
The US has said the draft is "unacceptable" and "unbalanced", because it makes no mention of halting the Hamas rocketing of southern Israel which led to the Israeli offensive.
|Smoke rises from the Jabaliya refugee camp in the Gaza Strip after an Israeli attack [AFP]
Most of the 1.5 million people in the densely populated enclave have no means of sheltering from the raids, and humanitarian groups say supplies of food and fuel are running dangerously low.
Hospitals have reported shortages of even the most basic medicines and say they have no more capacity to deal with the growing numbers of casualties.
Karen Abu Zayed, the commissioner for the UN Relief and Works Agency (UNRWA) in Gaza, said that in eight years of working in Gaza the need for aid had "never been so acute".
"I am appalled and saddened when I see the suffering around me," she said, adding UNRWA has made an emergency appeal for $34m to help the Gaza population.
Hasan Khalaf, Gaza's assistant deputy health minister, described the ongoing assault on Gaza as "an Israeli massacre".