Can we restrict FTPs account so that it only accepts logins from a specific IP address?
It is possible that the logins can be limited to certain IP addresses. The change would need to be done by altering the FTP configuration file, so you may want to look at the following article as well on how to update the configuration properly:
How can I make changes to my FTP configuration without cPanel overwriting my changes?
The information discusses here should only be performed by a qualified system administrator. The items mention here are not items that the cPanel Support Team can perform.
It does appear that the ProFTPD service does allow for connections to FTP to be limited by IP addresses. More details can be found in their documentation:
An example would be like the following:
Allow 18.104.22.168/24 22.214.171.124/24