According to Amazon\'s documentation, step function can be invoked using HTTP API.
Step Functions can be accessed and used with the Step Functions c
It's using HTTP API, not API Gateway.
Step function endpoints follow this format:
https://states.${region}.amazonaws.com
for example:
https://states.us-east-1.amazonaws.com
And you use HTTP API (again, not API gateway) to make actions on your states.
More about HTTP API here:
http://docs.aws.amazon.com/step-functions/latest/apireference/Welcome.html
Technically you could use API gateway, to redirect to step functions API but there's not much point in that.