The 19-year-old is the fifth Arsenal signing of the summer overall after the earlier captures Stephan Lichtsteiner, Bernd Leno, Sokratis Papastathopoulos and the aforementioned Torreira.
Emery, who replaced Arsene Wenger after the Frenchman stepped down in May, said a big club like Arsenal should always remain open to new signings but insisted he is happy with the squad he has available.
"In this moment I think the squad is complete, only the possibility for one player or two players to leave".
"Normally, in my career, the big clubs don't close the [door] or the moment to sign a new player", Emery told the press.
"Today, we are okay".
He said: "We signed the players who we needed and only if one player is a big opportunity for us will we sign them".
"Normally we are thinking about the young player, the possibility to stay with us or go on loan to another team".
"We are looking at, looking for, who are the players whose personality is the best in the dressing room".
Emery also downplayed reports that he's interested in reuniting with midfielder Steven N'Zonzi, who played under him at Sevilla.
"I know him [N'Zonzi] but we didn't do movement for him", he said.
The Gunners have been busy in recruiting the players identified by Emery, as well as head of football relations Raul Sanllehi and head of recruitment Sven Mislintat. His future is a question for the player and club.
"The information with Arsene is also important for me but the best is my direct relationship and conversations with the players".
On Ramsey, Emery Added: "I'm very happy with him". "Every training is with the ambition I want, working with quality and the competitive spirit I want".