Both players have been linked with moves to Old Trafford this summer, with the club reportedly confident of securing deals for the pair before the end of the window.
"Of course those two players are great," Silvestre told Goal.com.
"They are top players and will lift United. United is one club which is famous and everybody wants to go there, including the top players like Angel di Maria.
"I think they will be a good addition to the current squad."
United open their Premier League campaign at home to Swansea City on Saturday.