Silvestre said: "The only thing he said was that he wished me luck but was not pleased with my decision.
"After spending nine years at United it was a privilege to play for such a big club. It's also a privilege to now play for Arsenal.
"I still keep in touch with the United players. You build up strong relationships.
"This was one of the first games I put in my diary. November 8 is going to be a strange day but a lot of players have been through this and I am not worried about it."
Silvestre said: "Sometimes I had William on the phone but the only French part about this move was that I spoke to Arsene Wenger in French, which was easier.