The Brazilian midfielder missed Monday's 1-0 home defeat to Premier League title rivals Chelsea due to a thigh problem.
However, in a message on his official Twitter page on Thursday, Fernandinho revealed he expects to be available to manager Manuel Pellegrini in the near future.
He posted: "Good afternoon, I would like to tell you about my injury and quell rumours. I return to play in 15 days or less!"
City's first-leg tie against Barcelona takes place on February 18, with the return leg coming three weeks later.
Pellegrini's men sorely missed Fernandinho against Chelsea as they missed out on the chance to return to the top of the table.
The 28-year-old has featured in 20 Premier League matches and quickly developed into an integral figure for City since arriving from Shakhtar Donetsk in the close-season.
