"We tell the enemy and (Foreign Minister Avigdor) Lieberman who is threatening to reoccupy Gaza that the time for your threats is over," Haniya told a rally in Gaza City.
"Any aggression or crime or stupidity you commit will cost you a very high price."
On March 12, during a two-day flare-up in which Gaza militants fired at least 60 rockets into Israel and the Israelis responded with dozens of air strikes, Lieberman said Israel would have no choice but to reoccupy Gaza, from which it withdrew all troops and settlers in summer 2005.
"There is no alternative to a full reoccupation of the entire Gaza Strip," he told Channel 2 television.
Speaking to around 40,000 supporters at a public rally marking 10 years since an Israeli air strike killed Hamas spiritual leader Sheikh Ahmed Yassin, Haniya warned Israel that Gaza militants had "far more capabilities than you imagine".
He also restated his Islamic movement's opposition to peace talks between Israel and the West Bank-based Palestinian Authority of president Mahmud Abbas.
"Stop negotiating with the enemy," he told the PA. "We will not recognise Israel."
The memorial rally for Yassin -- the wheelchair-bound co-founder of Hamas killed on March 22, 2004 -- took place under the watchful eyes of hundreds of Hamas policemen who closed off streets around the central Al-Sarraya square and took up positions on rooftops.
Senior Islamic Jihad officials and members of smaller groups attended the event but Abbas's Fatah, Hamas's bitter rival, stayed away.
The Ezzedine al-Qassam Brigades, Hamas's military wing, sent threatening text messages to Israelis and foreign reporters in Israel on Saturday, the anniversary of Yassin's killing.
"If Gaza will be attacked the life of the Zionists will be hell" and "In the next war all the Land of Palestine will return," some read.
"Al Qassam has chosen you to be the next Shalit," another message stated, referring to Israeli soldier Gilad Shalit, who was abducted and held in Gaza for five years until Hamas freed him in exchange for more than 1,000 Palestinian prisoners.
The email account of an Israeli security affairs newsletter, Israel Defence, was hacked and an email posted on Yassin's killing. "We don't forget the blood of our sheikh, We swear again to take revenge, and this time by taking off the head of your leaders," it said.
SHI/SHI