Incoming traffic to Azure API Management's gateway can be secured to clients running in a virtual network through Azure Private Link. This will limit access to Azure API Management by assigning a virtual network private IP address to the Azure API Management gateway using Azure Private Link. Previously, only Developer and Premium tiers supported this integration with a virtual network. With this update, you can now integrate to clients in a virtual network privately, using the tiers Developer, Basic, Standard, and Premium.
Read this blog on how to secure your APIs with Private Link support for Azure API Management.
Review the documentation.