Labour leader Ed Miliband has urged supporters of Israel to feel optimistic about the prospects for peace in the Middle East.
He said his party was "deeply, deeply committed" to helping Israelis and Palestinians secure a two-state solution and again called on the two sides to resume talks.
Mr Miliband was cheered when he spoke at a Labour Friends of Israel fringe session at the party conference in Manchester on Tuesday evening.
He also railed against the rise of antisemitism in Britain, and said it had been "a very difficult few months in relation to what happened in Gaza".
"The priority now must be to, with great vigour and determination, take up the cause of meaningful negotiations for a two-state solution," Mr Miliband said at the packed reception.
"The reality that we all know is that whatever our particular views on the events, when you get a vacuum in the peace process the cycle of violence takes over. That's what we must change.
"Nobody in this room should be in any doubt of our opposition to the terrorism of Hamas and our condemnation of the rocket attacks we have seen."
In August Mr Miliband had called Israel's incursion into Gaza "wrong and unjustifiable" and attacked David Cameron's stance, but he steered clear of repeating those comments at the LFI event.
He said he had heard people's fears about antisemitism: "One of the most important things about our party is that we abhor prejudice, intolerance and antisemitism wherever we find it, in this country or
around the world.
"At these times we feel a sense of pessimism of what's possible. We should have a sense of optimism, but also an urgency of what must be done because we know that in many different ways the two-state solution feels further away and more imperiled than in a very long time.
"Our collective job is to do everything in our power to make it happen."
Mr Miliband spoke of the "incredibly moving experience" of going to Israel earlier this year and of meeting Israelis threatened by rocket attacks in Sderot.
He paid tribute to LFI chair Anne McGuire MP and to Adrian Cohen, chair of the London Jewish Forum.
Shadow Foreign Secretary Douglas Alexander was given a rousing reception by supporters despite having taken his own tough stance against the IDF operation in the summer.
He told the activists at the fringe session: "There have been weeks of great trauma, indeed crisis, across Israel, with the constant threat of rocket attacks.
"One of the consequences of the international controversy has been a disgusting rise in antisemitism here in the United Kingdom.
"I want to give you my word tonight: we will be unyielding in our opposition to antisemitism wherever it raises its head, whether it's within the Labour movement or outside the Labour movement.
"This is not the struggle of one community, it is our shared struggle and together we will confront and defeat the evil of antisemitism."
Mr Alexander said that the challenges facing the Middle East meant it was difficult to sustain hope, but urged supporters to keep in mind the "quiet warriors" - ordinary Israelis and Palestinians - who were working for peace.
The event was also addressed by Israeli ambassador to Britain Daniel Taub. He said there were "signs of opportunity" in the region and cited Arab countries taking a different stance towards Hamas during
the conflict.
But he said it was important for the international community to "step up to the plate" to make sure change was possible.
Among the leading party members attending the LFI session were Shadow Middle East Minister Ian Lucas, shadow cabinet colleagues Luciana Berger and Jim Murphy, veteran MP Peter Hain and Labour peer Lord Mendelsohn.
Leading Labour Knesset member Omer Bar-Lev also spoke of the challenges facing Israel.
