Goal.com revealed on Wednesday that the striker failed to impressive in the reserves in his first outing for five months after allegedly refusing to enter the fray against Bayern Munich last September.
The 28-year-old returned to training for the Citizens in February but Mancini has insisted that patience is required to allow Argentine to find full fitness and form.
“I think he needs a minimum of another two weeks,” the Italian told reporters on Friday.
“In these two weeks it is important he plays two or three games with the reserves. He needs to play on a big pitch.
“For him it is like pre-season, after three months it is not easy to play.
“At this moment he can't play. Maybe in two weeks he could be ready.”
City host Bolton on Saturday as they look to push further ahead at the top of the Premier League table, with nearest rivals Manchester United and Tottenham going head-to-head on Sunday.