Defoe has struggled to play regularly for his country but Lampard believes his importance cannot be under-estimated.
He said: "Jermain still has got an international future, without a doubt. I'm a huge fan of his, having known him at West Ham as a kid and watched his career.
"He is a goal machine. I love strikers that are hungry to score goals and he has got that about him.
"He has got that real sharpness and not many strikers could have scored that goal he scored, with the short backlift, the quick turn and finish.
"When you have got someone with an instinct like that for goal, you need them in your team or around your team because they can make something out of nothing."
Lampard added: "Managers have their choices. Maybe he hasn't always played at Tottenham for himself to be in there (with England).
"But I know when Jermain is in the team, you fancy he is going to get a goal because he is that sharp and he does it in training all the time. When players can make that difference, it is brilliant."