Israeli warplanes pummelled Gaza with 50 air strikes that killed seven Palestinians Saturday as militants slammed 23 rockets into Israel, defying international efforts to find a fresh ceasefire.
Britain, France and Germany on Saturday called in a joint statement for Israel and Hamas to agree a truce "immediately".
Tens of thousands of pro-Palestinian demonstrators marched through central London and Cape Town, condemning Israel's one-month military assault into Gaza.
Gaza emergency services said seven men were killed in Israeli raids -- two in a car driving in the southern Gaza town of Rafah, two travelling by motorcycle through Al-Maghazi refugee camp and three pulled from the rubble of Al-Qassam mosque in the middle of the enclave.
The Palestinian interior ministry said Israeli jets destroyed three mosques. At least two of them were considered close to Hamas.
Gazan Ibrahim Taweel said the Israeli military telephoned him at 3am, warning him to evacuate his nearby home five minutes before the mosque was attacked.
"I couldn't tell all my neighbours, so I evacuated myself and my neighbour and after five minutes an F-16 fired one rocket and after that a bigger rocket destroyed the mosque," he said.
The army said 23 rockets rained on Israel, bringing to 61 the number of projectiles launched at the Jewish state since a 72-hour truce ended on Friday.
One Israeli civilian and a soldier were wounded on Friday.
Israel said it had carried out more than 100 strikes in Gaza since Friday morning, 49 of them on Saturday, targeting those responsible for the rocket fire.
- Clashes in West Bank -
In the occupied West Bank, 15 Palestinian youths were injured in clashes with Israeli troops, who used rubber bullets and live fire to disperse stone throwers in the town of Hebron, medics told AFP.
The trouble broke out after the funeral of a Palestinian man shot dead by Israeli troops during protests against the Gaza operation on Friday, witnesses said.
Similar clashes also erupted in Ramallah. Israeli troops responded with tear gas and stun grenades.
The 72-hour truce collapsed after mediators in Cairo failed to extend a ceasefire when it expired on Friday morning as Israel accused Hamas of breaching the quiet with pre-dawn rocket attacks.
The conflict has now killed at least 1,913 Palestinians and 67 people on the Israeli side, almost all soldiers, since July 8.
The United Nations says at least 1,354 of the Palestinian dead were civilians, including 447 children.
In London, up to 150,000 protesters packed Oxford Street, marching to the US embassy and on to Hyde Park, many of them chanting "Free, Free Palestine" and holding up banners saying "UK - Stop Arming Israel".
Tens of thousands of demonstrators also marched through Cape Town to protest the Israeli military operation, one of the biggest rallies in the city since the end of apartheid.
Demonstrators carried placards stating "Israel is an apartheid state" and "Stop Israeli murder".
In Gaza, Hamas, which Israel brands a terror organisation, vowed no concessions.
"The occupier's intransigence will get it nowhere and we will make no concessions on the demands of our people," spokesman Fawzy Barhum said in a statement.
The lifting of Israel's land and sea blockade, imposed in 2006 after Hamas captured an Israeli soldier, has been a key demand of Hamas and the Palestinian Authority in Cairo talks.
A Palestinian official said on condition of anonymity Egypt and the Palestinians had reached a draft agreement for submission to Israel on Saturday.
It would see Egypt and the Palestinian Authority take control of the Rafah border crossing into Egypt, essentially activating part a unity accord Hamas signed with the PA in April.
Negotiations on the sea port, demanded by Hamas, would then be delayed and entrusted to the PA, with whom Israel is prepared to deal.
Israel waged the conflict to destroy Hamas's arsenal of rockets and its network of attack tunnels.
- Hopes of new truce -
But combat has not resumed at the same fierce intensity, feeding hopes of a new truce bring agreed.
"Our hope is that the parties will agree to an extension of the ceasefire in the coming hours," US State Department spokeswoman Marie Harf said.
Chris Gunness, spokesman for the UN agency for Palestinian refugees (UNRWA), called for the Gaza blockade to end so reconstruction can begin.
"Huge swathes of Gaza have been levelled. We cannot rebuild it with our hands tied behind our backs," he said. "The blockade must end."
At least 65,000 people have had their homes destroyed, and UNRWA said 222,000 people are still sheltering in 89 UN schools.
US-based Human Rights Watch said the knocking out of Gaza's only electrical power plant, by apparent Israeli shellfire, has worsened the humanitarian crisis.