Actually, the ESXi image that you have installed was a no-tools image, so you can reinstall ESXi with another image or follow the below instruction for install VMware Tools manually:
To download the VMware tools packages for various ESX/ESXi manually, see VMware Operating System Specific Packages.
To download the VMware Tools ISO image:
- Navigate to the link http://packages.vmware.com/tools/esx/index.html.
- Click the link for your version of ESX/ESXi.
- Click the link for your version of guest operating system.
- Download the VMware Tools ISO image and attach it to the CD of the virtual machine.
To know more about the error and resolution see:Resolution of the Error: the required vmware tools iso image does not exist or is inaccessible