I have SharePoint 2013 Foundation Server. I want to create a Workflow where i need to call a web service but i don't see that action in the action list.
Is this a limitation of this product or some installation missing on the server?
I dont think it is available for the Foundation, as you have to use the Workflow Manager in order to get the 2013 PlatForm workflows. But you cant configure Workflow Manager for SharePoint foundation. Check this
If you see below it is available for 2013 Workflow Platform.
Call HTTP Web Service Functions as a method call to an HTTP web service and returns data using the JSON format. Basic authentication is supported through the RequestHeader.
Workflow actions quick reference (SharePoint 2013 Workflow platform)