The agreement started at midnight local time on Monday and was brokered by Egypt.
Since the conflict began on 8 July almost 2,000 people have died, mostly civilians.
Quakers in Britain is calling for an immediate end to the violence and for the UK government to impose an arms embargo on all sides.
The organisation issued a statement after its Yearly Meeting held in Bath.
It said: "As we among other Nobel Peace Laureates have said, 'The conflict between the Palestinians and the Israelis will only be resolved when Israel's occupation of the Palestinian territory is ended and the inherent equality, worth, and dignity of all is realised.'
"Peace building is a long and demanding path to take... We long for - and will work for - a time when the fear experienced on all sides is replaced by a sense of security.
"The anniversary of World War I reminds us how easily militarised societies can slide into armed conflict and become blind to the alternatives to war.
"At such times, the international community has a responsibility to avoid fuelling the conflict.
"We join others in asking for a comprehensive arms embargo on Israel, Hamas and armed Palestinian groups.
"Quakers in Britain ask the UK Government to take a lead on this by halting arms exports to Israel."