Israeli President Moshe Katsav has rejected calls for his suspension, saying he is innocent of charges against him, which include rape.
Katsav says he is the victim of "public lynching"
Mr Katsav said in a statement that he was a victim of a despicable libel campaign.
Israel's attorney-general said on Sunday that the president should halt public duties while the allegations were resolved.
His non-binding legal opinion follows a request from the supreme court.
The government does not have the power to remove Mr Katsav, 60, from his largely ceremonial position.
Two weeks ago, Israeli police said they had enough evidence to charge Mr Katsav with rape, wire-tapping and other crimes.
He says that the allegations against him, made by a number of female employees, are all false.
"I am the victim of a despicable libel campaign," he said in a statement, quoted by AFP news agency.
"The authorities must not let the media lynch disrupt the investigation of the truth... I intend to fight to the end to prove my innocence."
A final decision on whether to bring charges is expected in a matter of weeks. He said he would wait for it rather than resign.
"The president is hurting, but is not afraid. The president is completely certain of his justice and innocence. All the authorities should wait for the end of the investigation, including the attorney general's final decision."
"Given the special position of the head of state, who symbolises the sovereignty of the state, it is necessary that the president suspend himself during this affair, so that it reflects what public opinion expects from the institution of the presidency," Attorney General Menachem Mazuz was quoted as saying.
He also suggested that if Mr Katsav failed to step aside, parliament should act as it is "the only body that can pronounce itself on the end of the president's mandate."
The father-of-five was elected for a seven-year term in 2000.
Correspondents say that while Mr Mazuz's opinion does not mean the embattled president has to resign, it piles further pressure on him to do so.