The trio were absent as Spurs suffered a 2-0 home defeat to Newcastle United on Saturday, although Sarr was sidelined with a hamstring problem.
Asked to explain their absence, De Zerbi said: "Richarlison, I don't know. He said too many times he wants to leave.
“Danso came to me two days ago and he said he wants to leave. Pape Sarr the same but he suffered a small injury, but he is almost ready to train.
"I love these players, and they are great guys. I have very good relationships. But if they want to leave, they have to bring the economic solution to the club, and they can go and we find other players."
Sources say Juventus are considering a move for Sarr, while De Zerbi confirmed all three players will be allowed to explore transfers.
Richarlison joined Tottenham from Everton in 2022, while Danso arrived permanently from Lens last summer. Sarr signed from Metz in 2021.
De Zerbi also urged supporters to remain calm after Tottenham lost their opening two league games without scoring, despite spending around £380 million on eight summer signings.