"In the struggle over the disengagement someone is likely to distort the rabbis' messages," Katsav told Army Radio on Monday.
The result, he said, could be "extremist actions" and "the distorted conclusion that to prevent Israel's destruction, one must assassinate the prime minister".
The Shin Bet security service on Sunday measured Sharon and members of his cabinet for bulletproof vests, a sign of increasing fears of violence against Israeli leaders ahead of the pullout due to begin in mid-August.
In recent weeks, some pro-settler rabbis have sharpened their rhetoric against the withdrawal from land they see as a biblical birthright, condemning it as a violation of Jewish law and a danger to Israel's existence.
Such talk has revived memories of verbal attacks on Prime Minister Yitzhak Rabin before his assassination in 1995 by an ultra-rightist Jew opposed to his peace moves with Palestinians.
Sharon intends to evacuate all 21 Jewish settlements in Gaza, which is home to 1.3 million Palestinians, and four of 120 in the West Bank.
Palestinians welcome any Israeli withdrawals from lands occupied in the 1967 Middle East war. However, they say they fear Sharon intends to leave Gaza mainly to cement Israel's hold on larger settlements in the West Bank.
Jewish settler leaders have called for passive resistance to the planned evacuation of the settlements.
Hardline Jewish settlers are
opposing Sharon's pullout plan
Hoping to sharpen that message, legislator Effi Eitam said on Israel Radio he planned to meet rabbis and settlers to draft a charter of non-violence to avoid clashes with Israeli soldiers during the pullout.
"In this charter we will have a clause specifying there cannot be any (settler) weapons in the evacuation area. We are trying to ensure that even if the atmosphere heats up, there will be a good chance of preventing a disaster," Eitam said.
Israeli security officials have said they plan to collect the army-issued weapons carried by many of the 8500 settlers facing evacuation.
"We have instructed the security forces in the Gaza Strip and northern West Bank to act with zero patience and zero tolerance towards any act of violence or lawbreaking," Defence Minister Shaul Mofaz said in a speech in Tel Aviv.
Last week, ultranationalists threw rocks at Israeli soldiers who evicted them from an abandoned house they had seized in a Palestinian neighbourhood adjoining a Jewish settlement bloc in the Gaza Strip.
During the violence, radical Jews stoned a Palestinian youth in what an Israeli general described as an attempted lynching.
"A Palestinian boy was lying there wounded and they were throwing rocks at him while an Israeli soldier tried to protect him. We cannot tolerate such sights. It violates the Ten Commandments," Katsav said.