The Italy international, who was a reported target of Manchester City this summer, has been locked in talks with Roma about a new deal for the last six months with his current contract expiring at the end of the season.
"It's not an easy negotiation," Fenucci said to Radio Rai. "It's an important deal and we have been discussing it over the summer.
"We have been able to define certain issues but, regarding the fixed amount [wages], there is still some distance.
"In any case, the will is there to reduce that difference in order to reach an agreement.
"Time is needed.
"Daniele is a great player, an excellent professional and this has been recognised.
"The club has an economic project. It has a revenue that is half of what the other three big [Serie A] clubs have and it has to work towards increasing the income."
Reports in Rome claim the 28-year-old De Rossi wants his wages increased to €6.5 million per year.