Roma general manager Franco Baldini admitted last week that Roma were willing to listen to offers for the 29-year-old midfielder.
De Rossi was sent off for punching Stefano Mauri in his side's 3-2 defeat to Rome rivals Lazio on Sunday, an incident that saw him dropped from the Italy squad for their friendly with France in Parma on Wednesday.
But Tommasi, president of the Italian Footballers' Association (AIC), is confident he will see out his contract in Serie A.
“I still see De Rossi as a Roma player..even if he did lose control at the weekend," he sadi.
“It was a really exciting game. It was just a shame about the red cards.
“I think there would have been more of a show in the second half if it was 11 vs 11, but Lazio, in my opinion, have a more balanced side.”