The Hornets conceded after just 38 seconds against the Citizens, and were lucky that the score only ended 3-1.
This defeat was Watford's tenth in their last 14 games, and speaking after the game Silva admitted that he is working on strengthening his defence by bringing in new recruits in the January transfer window, as quoted by Sky Sports.
"We are working. The board know what I expect. It's important with problems we have, if I have more players available for the next match it's important for us.
"I've got to work with the players in the squad and develop and improve them though. But I hope we can improve."
Silva has been without both Younes Kaboul and Miguel Britos in recent weeks, and admitted that his side are missing the duo and that their defending against City was nowhere near good enough.
"What I can say now is to come here, compete and do our best to take a good result when you start a game like this," he said.
"We weren't aggressive in our defence, it was too easy for them. The first 25 minutes we were too slow and we knew before the match they would push our team back.
"Against all teams home or away they do that. We need to do it in a different way and we didn't do that."
Watford host Carabao Cup semi-finalists Bristol City in the FA Cup on Saturday, and will be hoping that the Championship side won't cause any upsets this time around.