The International Committee of the Red Cross said in a statement on Thursday that it would ship 150,000 litres of diesel, enough to "help 13 public hospitals maintain essential health services for the next 10 days."
It did not say exactly when delivery would be made but an official said it would be "as soon as possible."
Gaza emergency services spokesman Adham Abu Selmiya said on Thursday that the health ministry's entire fleet of 37 petrol-driven ambulances were now out of service, leaving only 13—powered by diesel–on the road.
"All the ministry of health ambulances that use petrol have been put out of use... after the fuel ran out completely," he told AFP.
"We appeal to all the international and humanitarian institutions and people of conscience to urgently intervene," he said.
Abu Selmiya said the emergency services had access to another 40 vehicles able to transport patients but that these do not have the capacity of regular ambulances.
The Gaza Strip's sole power station shuddered to a halt on Sunday, running out of fuel just 48 hours after some 450,000 litres were delivered to the coastal strip from Israel.
"The current failure to ensure delivery of fuel and electricity could rapidly lead to interruptions in vital public services such as hospital care and water supply, putting the lives of thousands of patients in danger," Juan-Pedro Schaerer, the head of the ICRC delegation to Israel and the Palestinian territories, said in a statement Thursday.
"We have already warned that in the event of any such disruption, hospital operating theatres and specialist units, such as those providing intensive care, neonatal care and haemodialysis, would be especially hard hit."
The Gaza plant, which supplies nearly a third of Gaza's electricity, stopped generating power on 10 March, for the third time in four weeks, causing power cuts of up to 18 hours per day, according to the UN humanitarian agency, OCHA.
Gaza has long suffered outages because of shortages at its power plant, which has a maximum capacity of 140 megawatts but for some years has been able to generate only around half of that when operational.
In recent months, the situation has worsened because of a shortage of fuel, most of which is smuggled through cross-border tunnels from Egypt.