While the former Manchester United striker has shown exceptional form this season, scoring 10 goals so far in the Barclays Premier League, he has at times looked ill at ease.
Tevez was upset with Mancini when he taken off with a minute left in the 1-0 victory against Bolton and ended up being shunted away by the manager.
Not going quietly: Tevez was not happy with the decision to sub him against Bolton
The Argentina international is also struggling with bouts of homesickness after being separated from his family.
Quotes attributed to the player from his spells back home in South America have intermittently appeared, seemingly questioning his long-term commitment to European football and referring to his disillusionment with modern football.
Yet Mancini has no doubts though that his captain remains committed to the club in the long term.
'We can talk about this situation and talk about Carlos every week. I have explained it 1,000 times,' said the City boss when asked once again about Tevez's happiness at Eastlands.
'Carlos is a fantastic player. He is one of the most important players in Europe and maybe in the world. He will stay here for a long time because he not told me otherwise.'
Healthy return: Tevez has 10 Premier League goals for City this season
Tevez will nevertheless sit out the match against his former club West Ham on Saturday as he is banned along with left-back Aleksander Kolarov, who was sent off against the Trotters.
Mancini is unperturbed by the duo's absence and remains confident his side can produce the goods at Upton Park and extend their unbeaten league run to seven games in the process.
He said: 'Carlos and Kolarov are very important but the players who replace them can have a very good game.
'If we continue to play like we against Bolton and in the second half at Stoke (where City came away with a 1-1 draw) we can win without Carlos.'
Defender Kolo Toure is expected to be available after returning to training following a calf injury that resulted in him coming off at the weekend.
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