Argentine forward made way for Samir Nasri after pulling up just before the 30-minute mark as Roberto Mancini's side ran out 4-0 winners to maintain their unbeaten league start
The striker limped off during his side's 4-0 win over Blackburn Rovers at Ewood Park on Saturday with a groin injury.
The Argentine pulled up with the problem after less than half an hour of action and was replaced by Samir Nasri.
Speaking after the game, Platt said: “He’s not as bad as we first thought but it’s too early at the moment. It’s a groin injury, but the early indications are that it’s not as bad as we first thought.
"I think if we had a game in the week or next week then he wouldn’t play but with the international break who knows. It’s probably touch and go for him for Aston Villa but a lot will be made of it in the next 48 hours and then we’ll have a better idea. I would think at least two [weeks out] but I’m no medic.”
Aguero has scored eight Premier League goals already this season and any long-term injury would be a serious blow to City's hopes this term.
Manager Roberto Mancini announced that Aguero's Argentine team-mate Carlos Tevez would never play for the club again after he apparently refused to appear as a substitute against Bayern Munich in the Champions League in midweek, and losing Aguero in addition would cut his attacking options yet further.
Mancini will be relieved, however, that an international break follows this weekend's Premier League fixtures, which may allow Aguero time to recover before City play Aston Villa in two weeks' time.