It worked!! Thanks a lot for your help!! 
Here is my code:
Task in playbook:
-
name: ‘Generar Reporte’
become: yes
become_user: ‘{{site_name}}’
shell:
cmd: |
printf “GET services\nColumns: host_name description state\n” | sudo -u {{site_name}} /omd/sites/{{site_name}}/bin/unixcat /omd/sites/{{site_name}}/tmp/run/live
args:
executable: /bin/bash
register: reporte
-
debug:
var: reporte.stdout_lines
Inventory with site var:
[check_mk_prod]
your_hostname site_name=your_site_name