Aguero's Argentine teammate has been frozen out by the City management after failing to warm-up during a Champions League match in late September and his future at the club is still clouded.
Aguero admits it is not a very nice situation to be in and just hopes things are resolved as soon as possible.
"Unfortunately, the club and Carlitos haven't reached an agreement and it pains me, as an Argentine and a team-mate, it makes me sad," Aguero told ESPNDeportes.com.
"I can't get involved in defending Carlitos or the club because I don't know what happened.
"Only they know. It's a shame for everyone.
"Hopefully, in these days or the next month it can be solved and he will be with us."