Mancini, speaking in Vancouver where City are continuing their pre-season North American tour, told Sky Sports News: "We have an agreement with Corinthians but Carlos now is still a City player."
The Brazilian window for foreign transfers closes on Wednesday.
Last week, City rejected a 40 million pounds bid from Corinthians, where the Argentinian played for 18 months between 2005-06 helping them win the Brazilian championship in 2005.
Reports have said the English Premier League side want around 50 million pounds for the player who joined them two years ago from Manchester United.
Tevez says he wants to return to South America to be closer to his family and his two young daughters.
Brazilian championship leaders Corinthians, one of their country's most popular clubs, confirmed they were considering City's terms.
"Corinthians president Andres Sanchez said that there is nothing concrete regarding Tevez at the moment and that the terms will be analysed by himself and the board," said a statement on the club's website.
Mancini said he did not know the current status of the negotiations or whether personal terms had been discussed. Tevez was widely reported to be earning in excess of 200,000 pounds a week at City.
"I don't know this. I repeat, at the moment, Carlos is still a City player," he added. "I want to wait. At the moment we are here, we are working with the other guys. We should think about this."
CUP WINNERS
The player's advisor, Kia Joorabchian, said last week a deal with Corinthians was "close" with Tevez happy to return to one of his previous clubs, even though he was under contract to City for another three years.
Manchester City defender Joleon Lescott said he would be disappointed to see his team-mate leave but understood if he did.
"We'll be disappointed if Carlos leaves but it was down to the club and Carlos and what was best for each other and they have come to an agreement so I wish both parties all the best," he said.
"Carlos is his own man. Last season he played to 110 percent every game so none of us will be holding any grudges towards him and we'll wish him all the best if he does leave."
Tevez had indicated he wanted to leave City last October but was tempted to stay and played an influential part in guiding the club to third place in the Premier League and a berth in the Champions League for the first time.
City also won the FA Cup last season, their first major trophy since 1976, and have made no secret of their desire to become one of the biggest clubs in Europe.
With the spending power of the club's billionaire owner Sheikh Mansour of Abu Dhabi behind him, Mancini has already said he wants to sign Argentine Sergio Aguero from Atletico Madrid as Tevez's replacement if he leaves.
City also confirmed on Monday that left-back Jerome Boateng had completed his move to Bayer
