The Bees won 1-0 on Saturday with Dango Ouattara hitting an early first-half winner.
“Just disappointed about the result,” said Tielemans afterwards. “Obviously, we know we can do better, and we just want to show ourselves out there, and we didn’t do that today.
“I think we’re going to have to analyse the game and see what was missing exactly, but it’s true that some moments we were playing a bit too slow and could’ve done some better actions.
“Just the last pass or the last shot was missing. They defended well as well, so credit to them for their good defending, and it’s up to us to do better next time.”
On Villa's poor start to the season, the midfielder added: “Last season is gone. It’s up to us to do better, to improve as a team and just get wins in.
“We have to learn, improve and hopefully get a week of good work and get a win next week.”