Aguero, who has missed City's last three games, has been back in his native Argentina for treatment.
Manager Roberto Mancini said last Friday he expected the 24-year-old to return to Manchester early this week to resume training with a view to playing against Newcastle on March 30.
But having initially named Aguero in their squad for their forthcoming World Cup qualifiers against Venezuela and Bolivia, Argentina have taken the chance to check on the player's progress rather than play him.
Aguero said via Twitter: "My knee is better but the squad's physicians would rather have me be safe and stick with the treatments until it's completely healed.
"It's a pity to miss out on the national squad matches but I'll be cheering for Argentina from Manchester, while I finish the recovery."
