Dzeko, 31, is wanted at Stamford Bridge as Blues boss Antonio Conte looks to provide more support and competition for Alvaro Morata.
Speaking after Roma lost 1-0 at home to Sampdoria on Sunday night, Gandini suggested that an agreement was possible before Wednesday's transfer deadline but not straightforward as it must satisfy both clubs, Dzeko and his representatives.
"There are offers, we are talking and evaluating, but it takes three parties to reach an agreement and at times also with those who are around the player," Gandini told Sky Sport Italia.
Gandini added: "Nothing has happened yet, the market is open for everyone. Every club sells and that is ordinary activity.
"With the buying and selling of players, you work out a balance sheet, but also results. This month hasn't been the best, but the results and performances have been deteriorating ever since we achieved qualification for the Champions League knockouts.
"We had some setbacks and that took away from our confidence."