Emery opened up about the situation for the first time after overseeing the Gunners’ impressive 3-0 win over Colorado Rapids in the early hours of Tuesday morning.
Koscielny refused to join his teammates on the trip as he seeks to be released from his contract so he can move back to France.
The centre-back – who has one year left on his current deal – has been at Arsenal since 2010 after joining from Lorient.
It is understood that Bordeaux, Lyon and Rennes are all vying to sign the two-time FA Cup winner, who is valued at around £10m.
“I spoke with him three times for his situation”
Emery insisted in the post-match press conference that he spoke with Koscielny three times about the trip across the Atlantic and wanted him there.
The Spaniard said that the 33-year-old decided to stay home though and that the matter is now in the hands of the club.
“I spoke with him three times for his situation. We wanted him to come with us but he decided to stay. Now it is a matter for the club,” Emery said.
“He has one year more contract with us. For me he’s an important player.
“Now it’s one matter for him and the club. The club and him need to speak and they are speaking about his situation. I cannot say more than that.”
“I cannot say more about that. For me now it’s clear. We need to keep moving ahead.
“We’re playing with the spirit to create a new way. I’m waiting on his conversation and decision with the club.”
Emery also spoke about the importance of completing Arsenal’s first pre-season match and about how glad he was to see some of the younger players in the squad.
The starting eleven was made up largely of young prospects before several more senior players were given a run out in the second half.
Bukayo Saka, James Olayinka and Gabriel Martinelli netted the goals for the Gunners.
“Our idea is to give every young player chances to be with us, first in the training ground and after in matches,” Emery added.
“The idea is to continue working with them and give them chances. They will win chances to show us what you can do.”