England were trailing 2-1 when Lampard's 20-yard strike hit the underside of the bar and bounced down around a yard over the goalline.
But the match officials allowed play to continue and Germany eventually went on to win 4-1 - a scoreline Lampard believes flattered them.
The Chelsea midfielder said: "I haven't seen the goal again but I didn't need to see it again.
"I knew straight away that my shot was over the line, clearly a yard or so.
"It baffles me that it wasn't given and it was a big deciding factor.
"I won't stand here and say it is the reason why we got knocked out.
"But if it had gone to 2-2, and we had still come out and played the way we did in the second half, it would have been a different game."
Lampard said: "I think it is time to bring in goal-line technology.
"We had a meeting before the World Cup when we were told about a million different rule changes that hardly affect the game.
"The big one, the one that affects the game today, hasn't been brought in so it is a no-brainer."
Lampard believes there were only small margins that separated the two sides.
He said: "Everyone can see, it was small things in the game.
"Everyone can see it was a goal which would have sent us in level at half-time and after the break we were on top and hit the bar again.
"Maybe we showed a bit of desperation and a little bit of naivety on our part in trying to push and push and getting caught on sucker punches on counter-attacks.
"It is the story of the game. Nobody can stand here and tell me Germany were a lot better than us. They were not 4-1 better than us.
"But the things have conspired against us and maybe we have conspired against ourselves at times. But it just didn't go for us."