He told The Guardian: "It was definitely a yellow card. I said to the referee at half time that, as I have come inside, the leg was there and [Lampard] has pulled out at the last minute but I still went over, so it was a deserved yellow card.
"I have got to kick it out of my game. Everything happens so fast. I didn't have time to react to him pulling out at the last second. It's sort of instinct. You make mistakes and that dive was a mistake.
"I apologised to the referee and said I thoroughly deserved it and, hopefully, I won't do that again. It was a deserved booking. If there's contact, it's not a dive but he (Lampard) pulled out here."
Spurs have used Townsend consistently this season in a breakthrough start to the campaign for the starlet at White Hart Lane that also earned him a maiden England call-up last month.