The agreement, announced to the Security Council, could help curb Palestinian economic deterioration and shore up US-backed President Mahmoud Abbas's standing in Gaza, which since 2007 has been controlled by Hamas Islamists shunned by the West.
Serry said the United Nations had brokered the deal "to enable work at the scale required in the strip, involving the private sector in Gaza and giving a lead role to the Palestinian Authority in the reconstruction effort".
The agreement would "provide security assurances through UN monitoring that these materials will not be diverted from their entirely civilian purpose," Serry added, alluding to Israeli demands that cement and other imports not be used to build Hamas command bunkers and cross-border attack tunnels.
Fifty days of conflict in Gaza between Hamas and Israel, which ended late last month, has left swathes of ruin in the Mediterranean enclave of 1.8 million Palestinians.
Abbas's PA said in a study recently that the reconstruction work would cost $7.8 billion, two and a half times Gaza's gross domestic product, including $2.5 billion for the reconstruction of homes and $250 million for energy.
The World Bank said on Tuesday that the war would contribute to a reversal of 7 years of growth in the Palestinian economy, now expected to shrink by nearly 4 percent this year.
Gaza will see contraction of as much as 15 percent, while a slight recovery in the fourth quarter could push growth in the Israeli-occupied West Bank, where the PA holds sway, to about 0.5 percent, the World Bank said in a report.
It said the downturn was also a result of restrictions on the flow of goods into Gaza by Israel and neighboring Egypt and a drop in foreign aid to the Palestinian Authority.
"The conflict and humanitarian tragedy in Gaza has made an already struggling Palestinian economy worse and put further stress on the fiscal situation of the Palestinian Authority," the report said.
Egypt will host a donors' conference on October 12 with the aim of raising reconstruction funds, and donor nations to the PA are due to convene on the sidelines of the UN General Assembly next week.
"The lack of a comprehensive peace agreement leads to a vicious cycle of economic decline and conflict," the report said of efforts to clinch a deal on Palestinian statehood in the West Bank and Gaza that collapsed in April.
Growth, spurred largely by international donor funds, has been decelerating since 2012 and slowed to less than two percent in 2013 but could rebound strongly in 2015 if Gaza reconstruction gets under way, the bank said.
Its report, issued three weeks after a truce, said a strong world response to rebuilding needs could ultimately spur economic growth, helping it to top four percent in 2015, with Gaza growing by 11 percent if goods do flow into the territory.
Even without additional spending resulting from the war, the PA would face a financing gap - due in part to a fall in donor aid of about $350 million this year, the World Bank said.
A sustainable Palestinian economic future depended on international budget support for the PA and "sincere efforts" by Israel "to allow better and faster movement of people of goods", while taking into account its "legitimate security concerns".
"(This) must get up and running without delay, as an important step towards the objective of lifting all remaining closures, and a signal of hope to the people of Gaza," he said, predicting that donor confidence would also be boosted.