Several international airlines today halted flights to Israel indefinitely, citing security concerns after a rocket from Hamas-controlled Gaza Strip landed near Israel's biggest airport, Ben-Gurion International Airport in Tel Aviv.
Kerry flew into Tel Aviv from Cairo despite US warnings over airline safety and held hectic parleys in Jerusalem, also meeting UN Secretary-General Ban Ki-moon.
"We have certainly made some steps forward, but there is still work to be done," Kerry said.
Kerry, during his whirlwind tour of the region, will also meet Israeli Prime Minister Benjamin Netanyahu and Palestinian president Mahmud Abbas.
On US President Barack Obama's direction, Kerry yesterday held talks with Egyptian and Arab League officials in Cairo to push for an "immediate cessation of hostilities".
Ban also voiced guarded hope for ending the violence, as efforts to broker a truce in the the 16-day conflict hastened.
"We are now joining our forces in strength to make a ceasefire as soon as possible, but there is still some detailed way which we have to make," he said.
"We do not have much time to wait and lose," Ban said after speaking with Netanyahu in the morning.
The Israeli military said it hit more than 187 targets overnight, most of them in Shaja'ia, a neighborhood east of Gaza City near the border with Israel. The IDF said Hamas uses the residential area as a "fortress for its weapons, rockets, tunnels and command centers."
The death toll mounted as neither side showed any sign of backing down. Palestinian health officials said at least 649 Palestinians had been killed and 4,040 wounded. Some 70 to 80 per cent of them are civilians, according to the UN.
Twenty-nine Israeli soldiers and two Israeli civilians have also been killed in the conflict.
United Nations Relief and Works Agency (UNRWA) said more than 118,300 Palestinians have now taken refuge in its shelters. It says 43 per cent of Gaza has been affected by evacuation warnings or declared no-go zones.
In the latest incident, Israeli tank fire killed five people, including two children, in southern Gaza. Also, a foreign worker in southern Israel died after being hit by a mortar round fired from the Gaza Strip, police said.
In Geneva, UN rights chief Navi Pillay said Israel's military actions in the Gaza Strip could amount to war crimes, while also condemning indiscriminate rocket attacks by Hamas.