Hi Pradeep,
Sorry for delayed response.
Although I could not verify, I'd like to share my idea.
You said that you are using Git actin pack 10.3.1503.1. You can update it to 10.4.1507.1.
This release can handle empty username and password.
ftp://ftp.ca.com/pub/dpm/ReleaseAutomationActions/ActionPacks//nolio-git-actions/ActionPack.pdf
What's New
The following updates were made for 10.4.1507.
Git actions with empty username and password supported.
After that, clear Remote Repository Username and Password in you action, and set Repository like following.
ssh://<Username>:<Password>@<Repository server>:<Port>/<Repository path>
If the problem cannot be resolved, I recommend to use "Run Command Line" instead of Git action pack as second idea.
Git action pack may not handle private key with id_rsa and .ssh/config files.
When you use "Run Command Line" action type, please attention to user who executes RA Agent and directory of private key and config file.
If both ideas are not effective, please open a support case and attach logs Gregg mentioned.
Thanks
Yas