Dango Ouattara’s 12th minute goal was enough to earn the Bees their first points of the Premier League campaign.
Villa, by contrast, have failed to win either of their first two matches of the season for the first time in six years. It is also the first time they have failed to score in either of their first two games since 2002.
Emery blamed a slow start to the match for the defeat, with Villa bossing possession after going behind but failing to create much in the way of chances.
The manager, who has endured a frustrating summer in the transfer window due to the club’s need to remain compliant with Uefa’s financial fair play rules, is hoping to add some new faces to his squad before the September 1 deadline.
He said: “Finishing the transfer window next week we are going to clarify everything.
“My message is to keep calm, move on and do the work we are doing, also be strong in our mentality.”
Emery continued: “We lost the match today because the first 20 minutes we weren't really performing and playing with the intensity we needed.
“We reacted after conceding, dominated and created chances. They defended our corners and had transitions. We avoided their attacks in transition and we dominated.
“This is a very good example about how football is. Conceding the first goal, it is very hard to come back.
“We have to move on and continue working, trying to change some circumstances we have.”
Ouattara pounced after a mistake by Pau Torres, who replaced the suspended Ezri Konsa in the starting XI.
Villa looked for a response but saving a first half John McGinn shot was the only serious work for home keeper Caoimhin Kelleher.
“After we conceded the goal, the players responded, reacted, they tried,” said Emery. “The first 20 minutes, I am a little bit disappointed.
“Of course, to lose here is hard for us. But it happened.
“The message before the match was to keep the clean sheet - the first message - and then to try and win the match.
“We didn’t keep the clean sheet and we didn’t score the goal. Of course, we lost.”