Leaders in Israel and Palestine have been urged to “step back from the brink” by Boris Johnson after violence intensified.
Rockets were fired from Gaza while Israeli forces bombarded the territory with air strikes in the most serious fighting since the 50-day war in 2014.
The Prime Minister called for restraint and said the UK is alarmed at the mounting toll of civilian casualties.
Foreign Secretary Dominic Raab spoke to the Israeli foreign minister on Tuesday and will speak to the Palestinian prime minister on Wednesday, MPs were told in Westminster.
The sensitivity of the situation in the Middle East means ministers have to be careful in what they say – a point underlined as Lord Goldsmith deleted a tweet stating “no country on Earth would be expected to tolerate these incessant attacks on innocent civilians – by an organisation committed to their total eradication” adding “why should Israel?”
Asked about the deleted tweet from Lord Goldsmith, a Foreign Office minister, the Prime Minister’s official spokesman said: “There can be no justification for terrorist attacks on civilians, we do not condone the killing of innocent civilians under any circumstances.”
The spokesman stressed the Prime Minister had made his position clear in his message calling for restraint on both sides.
Hamas and other militant groups in Gaza have fired hundreds of rockets at Tel Aviv and other cities.
Israel has responded with air strikes targeting police and security installations, although the Palestinian authorities said there have been civilian casualties.
The death toll in Gaza rose to 48 Palestinians, including 14 children and three women, according to the health ministry.
More than 300 people have been wounded, including 86 children and 39 women.
Six Israelis, including three women and a child, were killed by rocket fire, and dozens of people were wounded.
The army also confirmed that a soldier – Staff Sergeant Omer Tabib, 21 – was killed in an anti-tank missile attack near the Gaza Strip, the first Israeli military death in the fighting.
Mr Johnson said: “I am urging Israel and the Palestinians to step back from the brink and for both sides to show restraint.
“The UK is deeply concerned by the growing violence and civilian casualties and we want to see an urgent de-escalation of tensions.”
The latest upsurge in violence has been triggered by tensions in Jerusalem during the Muslim holy month of Ramadan.
A focal point was the Al-Aqsa mosque compound, a holy site sacred to both Jews and Muslims, while there were also clashes over the threatened eviction of dozens of Palestinian families by Jewish settlers in the Sheikh Jarrar neighbourhood of east Jerusalem.
Shadow foreign secretary Lisa Nandy said: “There must be an immediate end to the rocket attacks and air strikes that risk further civilian fatalities.
“With the coordinated support of the international community, Palestinian and Israeli leaders must work to urgently de-escalate tensions. Anything less is an abject failure of responsibility which will lead to further suffering.
“Once this terrible violence has ended, we must ensure that the root causes of the conflict are recognised and addressed. International law must be adhered to.
“The eviction of Palestinians from their homes in occupied East Jerusalem has got to stop and all religious sites must be respected.
“At the same time, Britain and the international community must reinforce our commitment to a two-state solution.”