The United States on Wednesday urged Israel and the Palestinians to de-escalate the Gaza tensions and expressed concern for the safety of civilians on both sides as Israeli 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 had spoken earlier in the day with Israeli Prime Minister Benjamin Netanyahu and planned to speak with Palestinian President Mahmoud Abbas.

Psaki said US officials have been "encouraging all sides to de-escalate the situation," restore calm and take steps to protect civilians.

"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."

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