Mancinin plays down Rooney chances
United boss Sir Alex Ferguson has responded to intense speculation over Rooney's future by insisting the England striker will still be at Old Trafford next season.
But Mancini was still asked whether he might be tempted to test United's resolve over the 27-year-old as he met media to preview his side's FA Cup clash with Barnsley this weekend.
City were heavily linked with a move for Rooney during the player's infamous contract stand-off with United in 2010.
Mancini said: "I think that Rooney is one of the best strikers in Europe but I think it is difficult he can leave Man Utd - I don't think (so)."
Suggestions Rooney could leave United have gathered pace since he was omitted from United's starting line-up for their Champions League loss to Real Madrid on Tuesday.
Mancini says he would be surprised if something such as that led to his departure.
The Italian said: "I don't know. I don't know this situation.
"I can understand maybe Rooney would be upset if he didn't play but these are things that can happen in every team. After one week it is finished."
There has been a report suggesting City striker Edin Dzeko could hold the key to Rooney's future at United.
Dzeko has been linked with a return to German football with Borussia Dortmund, whose star striker Robert Lewandowski is reportedly coveted by United.
Were Dzeko, signed from Wolfsburg for £27million two years ago to move on, that could tempt Dortmund to cash in on Lewandowski 12 months before his contract expires.
But Dzeko, City's top scorer in the Premier League this season with 12 goals, has often stated his desire to remain at the Etihad Stadium and Mancini claims not to be aware of any interest.
He said: "At the moment, there is nothing. In the end, maybe, I don't know. In the summer, it could be possible.
"Dzeko player is an important player for us. We want that he stays here."
One of City's other high-profile strikers, Sergio Aguero, will miss the Barnsley clash with the knee injury that kept him out at Aston Villa on Monday.
Captain Vincent Kompany will also not be risked after missing six games with calf problems.
Mancini hopes both players will be fit to return for the trip to Everton next week.
Mancini said: "I don't think it is serious but in this moment we can't take a risk with Sergio.
"Vinnie was training with the team yesterday but I don't think we can risk Vinnie. Maybe he is ready for the next game against Everton."
Midfielder Jack Rodwell faces up to a month on the sidelines after limping out at Villa Park with yet another hamstring injury.
The 21-year-old, whose City career since a £12million summer move from Everton is yet to take off, has a history of such problems and only returned to action in January after a three-month lay-off.
Mancini said: "Jack is so-so. I think we need two or three weeks after the international break."