Gtk-WARNING **: cannot open display launching background GTK

I have centos 6 minimal (headless) as a Host and installed ubuntu 14.04 Desktop as a guest and using KVM. There is a web application deployed inside Guest, and it opens and closes one GTK application (javafx) in background.I am invoking this web app from my host thru ssh as "curl http://guest/myapp/start"I observed the logs in Guest OS and see the error message "Gtk-WARNING **: cannot open display"

I didn't understand the reason for this error.1) This GTK app is not opening any window physically in ssh console on host and moreover it's background.2) Guest is desktop version.

Can any one help me how to resolve this. I can't enable XWindows due to security requirements by the client.

Thanks,Sridhar