I'm not sure if anyone already answered your question with command line fix.

I'm a Linux/UNIX guy. So I used "gnu sed" on macOS to fix the issue as following:

1) Install gnu sed (gsed)

% brew install gsed

2) Replace a value with gsed

% cd ~/Virtual\ Machines.localized 

% grep ^serial0.present vmf-rhel7vm.vmwarevm/vmf-rhel7vm.vmx

serial0.present = "TRUE"

% gsed -i '/^serial0.present/ s/TRUE/FALSE/' vmf-rhel7vm.vmwarevm/vmf-rhel7vm.vmx

% grep ^serial0.present vmf-rhel7vm.vmwarevm/vmf-rhel7vm.vmx

serial0.present = "FALSE"

That's it. This should get rid of the message when you launch the VM.