Nainggolan has spoken highly of his Belgium international teammate and hopes to play alongside him one day.
“For me, he’s still a huge talent. We know each other and understand one another very well.”
The former Cagliari star told The Guardian earlier this month that new Chelsea manager Antonio Conte wants to sign him for the London outfit.
“He already wanted me when he was the Juve manager, but I’d already said I would never leave Roma for Juve,” said Nainggolan.
“Now he tries to get me to Chelsea. Conte told me what he expects from me and what type of player I can be for him."
The Belgium international scored six goals and created 42 chances in 35 Serie A appearances for Roma last season.
The midfielder had a pass accuracy of 85% and a shot accuracy of 40%, and won 21 headers, 27 dribbles and 52 tackles.
Meanwhile, Dembele enjoyed a successful season with Tottenham in 2015-16 and helped them qualify for the group stage of the 2016-17 Champions League campaign.
The Belgium international midfielder scored three goals and created 28 chances in 29 Premier League matches for Spurs last season.
The 28-year-old former Fulham man had a pass accuracy of 90% and a shot accuracy of 56%, and won 30 headers, 83 dribbles and 84 tackles.
Both Nainggolan and Dembele are on international duty at the moment, playing for Belgium at the ongoing 2016 European Championship in France.