Airlines blocked flights to Israel Wednesday after a Gaza rocket struck near airport runways, as the UN chief urged an end to a conflict that has killed 639 Palestinians and 31 Israelis.
As the violence entered its 16th day, neither Israel nor Islamist movement Hamas appeared willing to end hostilities, despite days of diplomatic efforts to coax them into a truce.
Palestinian emergency services said that at least six people were killed early Wednesday during prolonged shelling of the southern town of Khan Yunis and 20 more were wounded, most of them seriously.
Two more were killed by Israeli fire in the north of the Strip they said.
UN Secretary-General Ban Ki-moon, on a visit to Tel Aviv, appealed on Tuesday for the bitter rivals to "stop fighting" and "start talking.".
However Israel insisted it would keep up its aerial and ground assault until it smashes cross-border tunnels used by Gaza militants to attack the Jewish state.
A rocket crashed close to Tel Aviv's Ben Gurion international airport prompting the US Federal Aviation Authority to ban flights to and from Israel for at least 24 hours.
And the European Aviation Safety Agency advised all carriers to avoid Tel Aviv "until further notice".
The bans come after Malaysia Airlines flight MH17 was allegedly shot down by a missile over strife-torn eastern Ukraine, heightening sensitivity over aviation safety above warzones.
It was the first time such measures had been taken since the 1990-1991 Gulf war.
Israeli Prime Minister Benjamin Netanyahu appealed to US Secretary of State John Kerry to lift the ban.
"Netanyahu spoke this evening with ... Kerry and asked him to act to restore flights by American airline companies to Israel," sources in Netanyahu's office told AFP.
Kerry said the order would be reviewed within in a day and told Netanyahu the ban was solely due to safety concerns, State Department spokeswoman Jen Psaki said.
But US billionaire Michael Bloomberg said that he was flying to Tel Aviv by Israeli carrier El Al to show solidarity.
"The flight restrictions are a mistake that hands Hamas an undeserved victory and should be lifted immediately," the former New York mayor wrote on his official Twitter account.
Following top-level talks in Cairo, Ban went to Tel Aviv and appealed to both sides to lay down arms.
"Stop fighting, start talking and take on the root causes of the conflict so that we are not at the same situation in the next six months or a year."
The UN chief described Hamas rocket fire on Israel as "shocking" and said it must "stop immediately".
But he also said Israel must exercise "maximum restraint" in Gaza, and he urged it to take a hard look at some of the root causes of the conflict "so people will not feel they have to resort to violence as a means of expressing their grievances".
Meanwhile in Cairo, Kerry discussed ceasefire proposals with Egypt's President Abdel Fattah al-Sisi
The top US diplomat again placed the onus on Hamas to accept a ceasefire, backing an Egyptian truce initiative as a "framework" to end the fighting.
And a senior Palestinian official said talks were ongoing between president Mahmud Abbas and Hamas for a ceasefire.
Abbas pledged that Israel would be held accountable for Gaza deaths.
"We will pursue all those who commit crimes against our people, however long it takes," he said in televised comments ahead of an emergency meeting of the Palestinian leadership in Ramallah.
The meeting's concluding statement called for "widespread popular protest in solidarity with Gaza and the resistance."
Shortly afterwards, Israeli forces shot dead a Palestinian man in clashes at the West Bank village of Hussan, near Bethlehem, Palestinian security sources told AFP.
An Israeli army spokeswoman told AFP that he had been one of about of about 50 people throwing rocks and petrol bombs at soldiers.
"One of the protester