"We were not good enough in the first half and I accept that is my fault," Martinez said.
"Tactically, we could not cope with Spurs and the way they were moving the ball could not allow us to be effective."
The Wigan boss was without defenders Antolin Alcaraz and Emmerson Boyce, so Maynor Figueroa was shuffled to centre half.
"We have to cope with injuries at the back. That gives you instability," he added.
Rafa van der Vaart and Gareth Bale scored for Spurs before Mohamed Diame clawed one back for Wigan, but Martinez believes that the goals were weak.
"We conceded two goals which were very soft. Even though Spurs were dominant in the first half we were responsible for our own downfall."
Wigan currently sit at 15th place in the Premier League with five points from six games.