Security officials say clashes between Christian protesters and Egyptian security forces have resumed, with hundreds pelting the police with rocks outside a central Cairo hospital.
Days of protest in Egypt, ahead of elections expected to produce big wins for the Muslim Brotherhood, have stirred fears in Israel about bilateral ties and the future of the countries' peace treaty.
Israel had largely avoided comment on the unrest, which has seen dozens of Egyptians killed, but with protesters showing no signs of calling off their demonstrations, officials here have started to show concern.
On Wednesday, Israel's civil defence minister Matan Vilnai urged Field Marshal Hussein Tantawi, who heads Egypt's ruling military council, to bring the situation under control.
"The situation is problematic, sensitive and unclear. Tantawi is trying to avoid chaos and transfer power in the mostly orderly way possible," Vilnai told Israeli military radio.
"We hope that he will succeed... otherwise we will see general chaos and that will be very bad for Egypt."
Vilnai said Israeli officials were in "permanent contact" with members of the Supreme Council of the Armed Forces (SCAF), including Tantawi.
"I know him and he has no desire to stay in power," Vilnai added.
Egypt has been rocked in recent days by widespread protests, which come days before the first post-revolution elections, calling on the SCAF to guarantee a faster transition to civilian rule.
Protesters accuse the military of abusing its power and trying to write laws that would shield it from civilian oversight.
In Israel, the demonstrations and the elections have reawakened fears about the future of Egypt, bilateral relations and the country's peace treaty with the Jewish state.
Israeli officials and media commentators have made no secret of their concern about the rise of the Muslim Brotherhood, expected to perform well in the elections scheduled to begin on November 28.
"It's our main concern," Vilnai said Wednesday.
The top-selling Yediot Aharonot on Wednesday headlined its front page "Between Cairo and Tehran" in reference to the rise of Islamist forces in Egypt.
And the Maariv newspaper reported that Israel's army chief Benny Gantz "has presented to the security cabinet a scenario involving the cancellation of the peace treaty" between Egypt and Israel.
The report was denied by the military and Vilnai said it was premature to talk about the treaty being annulled.
"The cancellation of the treaty is not today -- and I stress the word today -- a reality," he said.
But he acknowledged Israel fears a serious degradation in ties with Cairo once a new government comes to power.
"But when Egyptian government stabilises after a long electoral process, we expect it will seriously undermine the accord," he said.
Nati Sharoni, a reserve general and president of a left-leaning Israeli think tank, sounded a more upbeat note, saying he expected the treaty to survive Egypt's upheaval and elections.
"The treaty will hold up fine, not for love of Israel but because it is in Egypt's fundamental interests," he said.
Danny Yatom, a former member of Israel's intelligence service Mossad, shared Sharoni's assessment.
"The accord is sponsored by the United States and the Egyptian army will continue to depend on American technology and subsidies after the elections," he said.
Still, Israeli officials are taking seriously the possibility of the treaty being cancelled or at least modified.
Israeli daily Haaretz reported the developments in Syria and Egypt formed the core of an annual presentation by all Israel's intelligence agencies to the country's security cabinet.
The newspaper also said Egyptian officials, including intelligence chief Murad Muwafi, have been at pains to reassure Israel, telling their counterparts the treaty is not in danger.