What you're describing is either a boot system that is not configured with serial console settings, or a VM that does not have a serial device added to it. In most cases, you will have to modify your installer boot options (specifically, kernel arguments) to include something along the lines of
console=tty0 console=ttyS0,115200. Also be sure that you have included a serial device in your virt-install line, as I do not see one added. I expound on this later in my answer.
You could use something altogether better suited to this whole task and use
virt-builder. This creates virtual machine disk images with fairly generic acceptable defaults in a minimal installation. It's a highly customizable tool, just as
virt-install is. Its man page is tremendously well-written.
virt-builder will grab signed virtual machine images from a few dedicated repositories and build a disk image file with those contents (disk image format depending on options chosen). For example, this following command will create a CentOS 7 disk image in qcow2 format, thinly allocated to 20GiB. It will also inject my public ssh key into root's home directory, as well as set the hostname to
fubar. Give the man page a good read, as the options go far beyond this.
# virt-builder centos-7 --arch amd64 -o /var/lib/libvirt/images/centos-7.qcow2 --format qcow2 --size 20G --hostname fubar --ssh-inject root:file:~/.ssh/id_rsa.pub
This disk image is ready to connect to a VM, which can be done using
virt-install, almost identically to the way you have done it in your question. There will be one big difference, in that we will specify
--disk so that we point to an existing image rather than make a new one. We also won't be specifying "size" within
--import excludes that option. Also note that I explicitly added a
--serial option, as we need to make sure that device exists to get a console on.
# virt-install --name vm1 --network bridge=br0 --ram=1024 --vcpus=1 --disk path=/var/lib/libvirt/images/vm1.qcow2 --import --nographics --serial=pty --os-type=linux --os-variant rhel7
This will start the "installer" which in this case is just starting the newly provisioned VM and connecting to its serial console.