Aguero has been sidelined since suffering a knee injury in City’s season-opening Premier League game against Southampton four weeks ago.
But despite the 24-year-old being ruled out at least until this weekend, that did not stop Argentina coach Alejandro Sabella naming him in his squad for this month’s World Cup qualifiers against Paraguay and Peru.
Mancini accepts Argentina had a right to call up the player to conduct their own medical assessment under the rules of the world governing body, but does not think it helped his recovery.
When asked if Aguero had remained in Manchester during the past fortnight, Mancini said: “No, because his manager wanted him there.
“He went there for five days, he worked with the physio. The Argentina manager wanted him there.
“This is a stupid rule because if we had a player who is injured for two weeks it is better he stays here.”
Mancini described the rule as “ridiculous” when he first heard of Aguero’s call-up and had hoped the player would be allowed stay in England.
Despite that, Aguero was due to undergo a fitness test prior to today’s encounter with Stoke.
The club’s £38 million (€47 million) record signing resumed training earlier this week in the hope of possibly featuring at the Britannia Stadium.
Ideally, Mancini would like to give his top scorer from last season a run out ahead of next Tuesday’s Champions League game at Real Madrid.
Mancini said: “Sergio is not 100% but his knee is okay. Maybe he could be on the bench.”
Mancini is pleased to be getting his side’s trip to Stoke out of the way early this season. City dropped two points when they last visited the Britannia Stadium in the Premier League in March.
That game came amid a difficult spell for City in which their championship hopes seemed to have been lost as they fell eight points behind Manchester United.
Yet after staging a dramatic recovery in the closing weeks of the season to pip United on goal difference, their fightback from 1-0 down to secure a point at Stoke was seen in a different light. Nevertheless, Mancini is glad the notoriously tricky trip is coming early in the season.
Mancini said: “We need to think only about Stoke because we never win there.”
For his part, Stoke boss Tony Pulis is mindful of putting too much pressure on new signing Owen. “I think by bringing Michael in now, we have got different options,” Pulis said.
“We’ll see how it goes — I don’t want to put too much pressure on him. I just want him to come and enjoy his football and get fit and sharp again at a club where he knows if he plays well, he will have an opportunity.”