With the Tevez wrangle expected to be resolved by the end of August, Smith and Rossi's futures have been the subject of intense debate.
Middlesbrough are rumoured to have made a substantial offer for Smith, while Parma are keen to keep Rossi, who scored nine goals in a 16-game loan spell to keep the club in Serie A.
Ferguson is trying to keep his options open as long as possible as uncertainty continues over Tevez's move.
But the United boss accepts that both Smith and Rossi will find their first-team opportunities limited if Tevez does eventually sign.
"We have had offers for Giuseppe, which puts us in a bit of a situation, while the quandary with Alan surrounds his long-term future and getting regular games," said Ferguson.
"There is no doubt Alan did fantastically well for us when he came back last season.
"He gave the team a spiritual lift and because he is such a fighter, he was an inspiration to us. But he is 26 now and he wants regular football.
"I have to look at Manchester United in terms of how do we improve to get better. And when someone like Tevez comes along, it makes it difficult for people like Alan and Giuseppe in particular.
"The most important thing is that they are our players and we can make decisions when we like."
Meanwhile Ferguson has admitted he lodged a bid for another striker earlier this summer.
Ferguson opted not to name the player but Bolton's Nicolas Anelka was rumoured to be a strong target, while the agent of Fabio Quagliarella, who scored 13 goals for Italian outfit Sampdoria last term but has since had his contract bought out in its entirety by co-owners Udinese, claimed six weeks ago United had bid £10million for the 23-year-old.
"We did try to get another player," confirmed Ferguson.
"It is obvious they are not going to sell at this particular time but we have our tabs on the situation."