The ruling Palestinian movement, Hamas, and its rival Fatah have agreed to renew a truce, a day after it crumbled.
Fighting has left dozens dead since the end of last year
The deal came after fighting in the Gaza Strip left 20 people dead and at least 100 wounded in the past 24 hours.
In Washington, the Quartet of Middle East mediators - the EU, the UN, the US and Russia - voiced its "deep concern" about the levels of violence.
The Quartet also supported a US push to revive the stalled peace process between the Palestinians and Israel.
In Gaza, the BBC's Alan Johnston says Hamas and Fatah leaders promised to withdraw their fighters and remove their checkpoints.
But even while the factions were spelling out the new deal, clashes continued and the Fatah delegation to the talks came under fire as it left the meeting, with two bodyguards injured, he says.
The recent battles were among the bloodiest since Hamas won elections a year ago.
Reports say Palestinian Authority President and Fatah chief Mahmoud Abbas and Hamas political chief Khaled Meshaal will meet in Saudi Arabia next Tuesday to try to end the fighting.
Hamas and Fatah have been trying to form a unity government for months.
They are deadlocked over Hamas' rejection of international calls that it recognises Israel.
Western donors have been withholding aid, resulting in a deep economic crisis in the Palestinian territories.
In Washington, the Quartet of Middle East mediators "called for Palestinian unity in support of a government committed to non-violence, the recognition of Israel and acceptance of previous agreements," UN Secretary General Ban Ki-moon said on behalf of the group.
The Quartet re-affirmed that a year-long aid embargo against the Hamas government would remain in place until it agrees to recognise the Jewish state and renounces violence.
But Russian Foreign Minister Sergei Lavrov expressed Moscow's strong scepticism over the boycott, describing it as "counterproductive".
He also spoke in favour of bringing Syria into the Middle East peace dialogue - a suggestion that was ruled out by US Secretary of State Condoleezza Rice.
The Quartet also backed US efforts to jump-start the so-called "roadmap" for a peaceful settlement between the Palestinians and Israel.
Ms Rice said tough topics had to be addressed to move the process forward.
"There's simply no reason to avoid the subject of how we get to a Palestinian state," Ms Rice said.
Three-way talks between Ms Rice, Mr Abbas and Israeli Prime Minister Ehud Olmert are expected to be held later this month.