The United States on Wednesday urged Israel and the Palestinians to de-escalate tensions in Gaza and expressed concern for the safety of civilians on both sides as Israel pressed a campaign of air strikes and militants kept up rocket fire at Israel's heartland.

State Department spokeswoman Jen Psaki told a briefing that US Secretary of State John Kerry, who is in China, had spoken earlier in the day with Israeli Prime Minister Benjamin Netanyahu and planned to speak with Palestinian President Mahmoud Abbas "over the next 24 hours."

Psaki said US officials have been "encouraging all sides to de-escalate the situation," restore calm and take steps to protect civilians. She said White House Middle East coordinator Philip Gordon was in Jerusalem and the West Bank on Wednesday and had met with Abbas.

"We are concerned about the safety and security of civilians on both sides," she said, referring to "the residents of southern Israel who are forced to live under rocket fire in their homes and the civilians in Gaza."

Psaki underscored the US view that Israel has the right to defend itself against the rocket attacks.

"Certainly, no country should be expected to stand by while rocket attacks from a terrorist organization are launching into their country and impacting innocent civilians," Psaki told reporters, referring to Hamas.

In discussions with Netanyahu, she said Kerry had expressed US "willingness to engage in helping to stop the rocket fire and restore the 2012 cease-fire as soon as possible."