Israeli President Moshe Katsav has warned that right-wing nationalists could attempt to assassinate Prime Minister Ariel Sharon.
Jewish protesters are trying to resist the withdrawal
Mr Katsav warned that the vocal opposition of pro-settler rabbis to Israel's Gaza pullout plan could incite extremists to take "dramatic measures."
Settler leaders have issued a code of conduct to deter their supporters from violent acts during the withdrawal.
The code was launched after violence erupted at settler protests last week.
Israeli police arrested a number of Jewish settlers during the clashes in the Gaza Strip and Jerusalem.
During the violence, militant Jews stoned a Palestinian youth in what an Israeli general described as an attempted lynching.
On Sunday, Israeli police arrested an eighteen-year-old West Bank settler in connection with the incident, which was condemned by Israeli politicians and the media.
Opinion polls suggested that support for the Gaza withdrawal plan had risen sharply after the violence.
"Attempts to physically harm people, to attack roads are things we cannot accept," said right-wing MP Effi Eitam who helped agree on the code.
As the date for the withdrawal from Gaza approaches, President Katsav voiced his fears that extremists might make an attempt on the life of Ariel Sharon.
He noted that the atmosphere was similar to the period preceding the 1995 assassination of then Prime Minister Yitzhak Rabin by an ultra-nationalist opponent of his peace deal with the Palestinians.
Mr Katsav called on pro-settler rabbi's to moderate their language, telling Israeli Army Radio "in the struggle over the disengagement someone is likely to distort the rabbis' messages.
The result, he said, could be "extremist actions" and "the distorted conclusion that to prevent Israel's destruction, one must assassinate the prime minister".
Mr Katsav made his comments a day after the Israeli internal security service Shin Bet measured Mr Sharon and members of his cabinet for bullet-proof vests, a sign of their mounting fears of violence ahead of the pullout due to begin in mid-August.
The pullout will see the removal of settlers and the soldiers that protect them from all 21 Gaza settlements, and from four out of 120 in the West Bank.
The Israeli army has begun to remove the temporary homes of its soldiers based in Gaza in preparation for the beginning of the withdrawal operation.
The military has also announced that it plans to seize 52 acres of Palestinian land in the West Bank to house soldiers involved in the operation to evacuate four settlements there.
The Israeli military's Civil Administration described the seizures as a 'rental' and said they would be a temporary measure.