I got /var partition running out of disk space. So cleared all unwanted files. Now I got 3.5GB free out of 10GB. It is also updated in WHM Server Information.
But not updated in WHM Service status.
Due to this, New account creation stopped with the following error message.
"The /var partition on this server is running out of disk space. WHM operation has been temporarily suspended to prevent something bad from happening. Please ask your system admin to remove any files not in use on that partition."