Make sure to install

yum -y install qemu-kvm qemu-img virt-manager libvirt libvirt-python python-virtinst libvirt-client virt-install virt-viewer
yum -y install kvm libvirt python-virtinst virt-top virt-manager virt-v2v virt-viewer vim pv

Make sure to start/enable – Note: a reboot might be required

servicectl start/enable libvirtd.service libvirtd.socket libvirt-guests.service

Now run
virt-manager