Thats a great request. What kind of action do you want to do as part of Invoking an Internal URL? I'm assuming the endpoint is an internal API.
As an alternative solution, you can execute the same api inside a shell or a powershell script and configure it at the monitor or attribute level and execute the script as the Automation. The steps are mentioned in this help documentation. You need to install the server agent in your poller machine.
Let me know if this would help you.
Product Manager, Site24x7