There is a list published by the IDF of "dual use" items that could be used for both innocuous and malicious purposes that are restricted from entering Gaza, like metal pipes that can be used to build rockets.
So-called "human rights" organizations routinely rail against these restrictions.
But read about the sanctions that the EU imposes on Libya:
- The European Union introduced in 2017 restrictions on the export or transit of inflatable boats and outboard motors to Libya.The reason is to help limit human trafficking from Libya.
There are exceptions for, say, fishing boats, but Israel allows exceptions as well for clear humanitarian needs where the materials can be accounted for.
When the EU does it, they are "sanctions." When Israel does it, it is a "siege."
(h/t Irene)