Israel has launched a ground offensive in Gaza with residents reporting heavy shelling in the area.
Palestinian health officials say 27 Palestinians, including a baby, two children and a 70-year-old woman, have been killed since Israel sent ground forces into the densely-populated strip of 1.8 million Palestinians.
David Cameron said Israel "has a right to defend itself" with Hamas launching rockets into the country as the Middle East crisis continues to escalate.
The death toll in Gaza continues to rise with at least 172 Palestinians dead in the week-long conflict.
The Prime Minister said: "It is a concerning situation but we should be very clear about two things; one is that Hamas has been firing rockets continually into Israel and secondly, Israel has a right to defend itself as a sovereign country that's been under attack.
"But, obviously everyone wants to see this situation come to an end, de-escalate and make sure people can live in peace and security."
It's been an emotionally exhausting day in Israel and Gaza as hopes for peace were raised then dashed then raised then dashed again.
In the court of international opinion, this is how Israel wins a battle and still manages to lose the war.
Until the Israelis and the Palestinians find a way of resolving the underlining conflict this will not be more than a pause.