Johnson failed to pin down a regular spot in the City manager's first team last season and could find playing time even more limited this term if the big-spending club complete a swoop for Arsenal's Samir Nasri.
The 24-year-old has been linked with loan moves to Everton and Sunderland this summer, but Mancini has made it clear the winger remains in his plans.
And Johnson believes fighting for a place in City's star-studded squad is part and parcel of being at a high-profile side.
He told The Sun: "I know the manager has said he wants another winger. But with the players we've got here, most of us know we won't play every single game.
"That's just part of being at a massive club like this. Two players for every position is good but if it was any more than that it would be difficult to get a game."
Johnson is pleased that Mancini has confirmed he has a part to play at the Etihad Stadium this season.
He added: "When you get linked with other teams you start to wonder if you are in their plans. But it's brilliant he's said I am.
"I had a lot of conversations with the manager, some things I agreed with, some I didn't.
"Whether it was right or not though, he's definitely brought me on as a player. I understand him a bit more now."
Source: Team Talk
Source: Team Talk