Josep Borrell described the lack of aid entering the territory as a "manmade" disaster.
A Spanish ship carrying desperately needed food supplies has left Cyprus for Gaza, but the UN says this cannot replace the delivery of aid by land.
Israel's Prime Minister Benjamin Netanyahu has meanwhile vowed to press on with an offensive in southern Gaza.
The quickest, most effective way to get aid into the territory is by road, but aid agencies say Israeli restrictions mean a fraction of what is needed is getting in.
Attention has instead shifted towards alternative routes including sea and air drops.
Israel says it is not to blame for Gaza's food shortages as it is allowing aid through two crossings in the south.
But addressing the UN Security Council in New York on Tuesday, Mr Borrell said the humanitarian crisis in the territory was as a result of a lack of viable land routes.
"We are now facing a population fighting for their own survival," he said.
"Humanitarian assistance needs to get into Gaza, and the European Union is working as much as we can in order to make it possible.
"[The humanitarian crisis is] manmade and when we look for alternative ways of providing support by sea, by air, we have to remind [ourselves] that we have to do it because the natural way of providing support through roads is being... artificially closed.
"Starvation is being used as a war arm and when we condemned this happening in Ukraine, we have to use the same words for what is happening in Gaza."
BBC