The 28-year-old said that both players have settled in well with the Rossoneri.
"Poli is a midfielder of quality and quantity," Montolivo told Milan Channel. "He's a concrete player who will be very useful.
"As for Silvestre, he did well in the recent game against Chelsea. He has only just arrived, but he has immediately fitted well into the mechanisms of the team."
Poli - an Italian international - joins from Sampdoria, while Silvestre is on a short-term loan from Inter Milan.