Speaking after meeting Egypt's president and foreign minister in Cairo, Guterres also warned of the impact the war in Gaza was having around the globe.
"The daily assault on the human dignity of Palestinians is creating a crisis of credibility for the international community," he said.
Guterres is visiting Egypt and Jordan as part of an annual Ramadan solidarity tour to Muslim countries and travelled on Saturday to Egypt's border with Gaza, where he called the backlog of aid destined for the Palestinian territory a moral outrage.
While more than five months of war between Israel and Hamas have shattered Gaza, donations of aid have piled up in Egypt's northern Sinai, with limited amounts sent in through Egypt's Rafah Crossing and the Israeli crossing of Kerem Shalom.
As hopes for a truce in Gaza during the Muslim holy month of Ramadan have faded and the risk of famine in the coastal enclave has increased, the United States and other countries have sought to use air drops and ships to deliver aid.
U.N. aid officials say deliveries can only be scaled up by land, accusing Israel of impeding relief, which Israel denies.
Sending in large quantities of aid requires Israel to remove the remaining obstacles and choke points to relief, Guterres said.
"It requires more crossings and access points," he said. "The only efficient and effective way to move heavy goods is by road. It requires an exponential increase in commercial goods."
Guterres said the United Nations was working hard to sustain funding for its agency for Palestinian refugees, UNRWA, which he called the backbone for humanitarian aid inside Gaza.
Several countries, including the United States and Britain, paused their funding to UNRWA after accusations by Israel that a dozen of the agency's 13,000 staff in Gaza took part in the Oct. 7 Hamas attack in Israel.
UNRWA head Philippe Lazzarini said he regretted Washington's decision to continue a ban on U.S. funding for the agency until at least March 2025.
"We very much regret Washington's decision," Lazzarini was quoted as saying by Swiss newspaper Blick on Sunday. "It's a halt for a limited period. Next year, we again have the possibility to apply pressure for a new decision."
