UK Prime Minister Boris Johnson called for a "durable solution" between Israel and Palestine after a ceasefire came into effect.
The Egyptian-brokered truce between Israel and Hamas began early on Friday, ending the worst violence in years.
Israeli air strikes in Gaza killed 232 Palestinians, and damaged thousands of homes and critical infrastructure. Gaza rocket attacks killed 12 people in Israel and wounded hundreds.
Mr Johnson called for new measures to “end the cycle of violence”.
“I welcome news of a ceasefire in Israel and Gaza,” he said on Twitter.
“Leaders in the region must now work to find a durable solution to the Israeli-Palestinian conflict that prevents terrorism, ends the cycle of violence and delivers a sustainable and just peace.”
European Commission President Ursula von der Leyen said both sides could now build on the truce.
"I urge both sides to consolidate it and stabilise the situation in the long term,” she said.
“Only a political solution will bring lasting peace and security to all.”
Josep Borrell, the EU's foreign policy chief, said the situation in the Gaza Strip was unsustainable.
"Restoring a political horizon towards a two-state solution now remains of utmost importance," he said.
"The EU is ready to fully support Israeli and Palestinian authorities in these efforts."
German Foreign Minister Heiko Maas said the ceasefire was a chance to address the causes of the conflict.
"It's good that there is a ceasefire and that there are no further victims," he said.
UN Secretary General Antonio Guterres called for dialogue between leaders from both sides.
"Israeli and Palestinian leaders have a responsibility beyond the restoration of calm to start a serious dialogue to address the root causes of the conflict."
Both Israel and Hamas claimed victory in the conflict. Fighting began in Gaza on May 10 after weeks of rising tension in occupied East Jerusalem.