Everton announced the arrival of Iwobi from Arsenal on deadline day in a deal thought to be worth up to £40 million ($48m).
The Nigeria international was widely thought to be a back-up option, as the Merseyside club were heavily linked with Zaha in the latter stages of the window and reportedly had offers knocked back by Palace.
The Ivorian ended up staying at Selhurst Park despite being the subject of interest from Arsenal as well, who also had bids rejected by the Eagles.
On the eve of Everton's trip to Selhurst Park for their opening Premier League match of the season, Silva has insisted he is "happy" with his side's overall transfer business despite failing to land Zaha.
He said at his pre-match news conference: "When you are planning a squad you plan with some names, and I did my job with the names to my football structure. We cannot just have one name.
"The market was difficult and when we lost [Ademola] Lookman we looked for a winger, not two wingers. We have tried to do the deals and we've signed a good player. It was not just our club that had an interest in Zaha.
"We are happy. We always want more, but we are happy."
Iwobi spent four years in Arsenal's first team after graduating from their academy and was used 51 times in all competitions last season, scoring six goals.
Silva talked up the versatility of the 23-year-old, who has never scored more than three times in a single league campaign, but admitted his latest signing needs to improve in front of goal.
"The position we are looking for him is clear - coming inside from the left," Silva said. "He can also play behind the striker really well and if you need to play him on the right he can do that also.
"He's a strong player with good skills. One thing I will be demanding from him will be scoring more goals, because it's important in that position.
"But he will help us. He's a strong player as you know, a fast player, and he can put good intensity in a match which I like from my attacking players. He will give me different solutions."