Newcastle started the quickest at Villa Park and Lambert thought that ultimately that was the difference.
Hatem Ben Arfa gave Newcastle the lead in the first half before Yoan Gouffran scored the winner after Christian Benteke's header had drawn Villa level.
Lambert said: "In the first half we never played. We lost two poor goals but in the second period we did better.
"We have to defend better as a team. We don't have a blame culture at this club but we must do better as a team.
"When we equalised we were on top but the second goal is a terrible one to give away. We were also luck to be only one goal down at half-time.
"Going forward we will always try and create but you can't give sides a start like that. "