Aguero has allayed fears that he could face a lengthy spell on the sidelines after being stretchered off against Southampton.
The City forward took a heavy blow to the knee in a tackle by Nathaniel Clyne in the early stages of Sunday's 3-2 home win over Southampton.
There was speculation that the Argentina international could miss much of the season if there had been ligament damage to the knee and manager Mancini was clearly concerned.
But the 24-year-old moved to calm supporter via his Twitter account @aguerosergiokun late on Sunday night.
He wrote: "The studies I had done revealed there's no significant injury but it was a very tough hit to my knee.
"Tomorrow the surgeons will evaluate the time it will take for me to recover.
"I can't muster words to thank you for concern and with this much support, I'll probably get back up on my feet soon.
"And I want to congratulate my team-mates for their effort in turning the game around."
After the match, Mancini had said it would be 48 hours before City could make a proper diagnosis.
"I am worried," said Mancini.
"We don't know how serious it is because we need to wait maybe two days for the scan.
"But usually the knee is dangerous.
"The injury was so strange because it was not a bad tackle. It was not strong.
"The good thing was that he wanted to try and play. But at the moment we can't say anything."
Mancini added that if the worst was confirmed later this week and Aguero was ruled out for an extended period, he may have to change his squad building plans.
He is still hoping to bring in a new face, with strong rumours linking him with Roma midfielder Daniele De Rossi, although Mancini said he knew nothing of any developments.
"If it is a serious injury, we will probably change our plans," said Mancini.
"But we need to wait. Maybe it will be one week or three or four weeks, after the international break."
Mancini also confirmed the complete absence of Adam Johnson from his matchday squad was to give the winger an opportunity to look for another club.
Johnson was at the Etihad Stadium on Sunday afternoon and trained with a number of team-mates after the match had finished.
However, he has become tired of being a bit-part player with the Blues, although Mancini insisted he has no axe to grind against Johnson, who started England's midweek win over Italy in Berne.
"Adam is a young guy," said Mancini.
"He is a good player and he wants to play.
"In these 10 days, if we find a good solution for him and he can go to play, maybe it is better.
"I don't know about a loan. We have two or three situations. We are talking with him about this.
"But if he stays here, I don't have a problem."
It formed additional talking points from yet another 3-2 win, which matched exactly both the scoring sequence and ends the goals were scored in from that momentous title-winning triumph over QPR in May.
The only difference was that on this occasion, City also missed a penalty, a woeful attempt by David Silva when the game was still goalless.
Carlos Tevez broke the deadlock just before the break, then Southampton substitutes Rickie Lambert and Steve Davis hit back to threaten a shock win for the newly-promoted outfit.
However, their lead lasted just four minutes as Edin Dzeko levelled - just as he did against QPR - before Samir Nasri drove home the winner 10 minutes from time.
"We didn't play well and we didn't defend well," said Mancini.
"But it is not always their fault.
"When a team like us has 10 chances to score, you should close the game.
"The second half I think we played so-so for many reasons and the players were so-so."
