On Wednesday the Eastlands club confirmed the signing of the winger from Valencia on a four-year contract for a fee believed to be in the region of ¦pound;25million. The 24-year-old Spain international will have a medical upon his return from the World Cup in South Africa when the transfer will be formally completed.
"I think that David Silva is one of the best midfielders in Europe, and I hope he will be a very important player for Manchester City," the Italian said.
"I am so pleased he is coming to us, I think he can make a big, big impact for Manchester City."
City narrowly missed out on a Champions League place last season, and Mancini believes Silva can help his side challenge for the title this time around.
He added: "In signing David, we are showing the world that we are bringing the best players here and that we hope to compete to win the Premier League.
"When players see what is happening at Manchester City and the ambition, they are attracted to what we are building and want to be a part of it."
City are again expected to be highly active in the transfer market this summer and a deal for Barcelona midfielder Yaya Toure is also thought to be close.
That would unite the Ivory Coast international with his brother Kolo, the City captain.