Arriving for the meeting of foreign ministers from the 27 EU states, Mr Hague made it clear Britain blames Gaza's Hamas rulers for precipitating the conflict, but also urged Israel to "de-escalate" the violence.
Mr Hague said: "We want efforts to negotiate a ceasefire to succeed. I spoke to the Egyptian foreign minister about that yesterday and Egypt are making strong efforts in that regard, with our support.
"Of course, part of any ceasefire has to be a cessation of rocket attacks against Israel, but everyone has responsibilities. Israel has responsibilities too to take every opportunity to de-escalate the violence, to avoid civilian casualties, to observe international humanitarian law. The Prime Minister and I have both spoken to our Israeli counterparts over the weekend."
Labour leader Ed Miliband said: "The deaths in Gaza and Israel are horrifying. It is a very dangerous moment not just for Israel and the Palestinians but for the region. A halt to violence on both sides is now absolutely critical."