I am trying to call a Lambda Function through AWS API Gateway.
When I mention Authentication type NONE it works fine but API become public and anyone with url can access my
Make sure you are clicking on the specific Resource first in the Stages tree, as that will populate a URL with the full path to the resource (rather than just the root path):
For other causes, see http://www.awslessons.com/2017/aws-api-gateway-missing-authentication-token/