But the Celtic manager retains total confidence the striker who started with two goals in his first three games, but has failed to fire since then, will have an important contribution to make this season.
The 23-year-old is travelling to join up with the Finnish national team for their World Cup qualifier against France.
When Pukki returns to Lennoxtown next week, Lennon is ready to reiterate that he remains convinced he has the ability to prove he was well worth the £2.4million outlay.
"Maybe Teemu is trying too hard to get a goal," is Lennon's frank assessment of the striker's recent shoot-on-sight approach.
He added: "But I was pleased with his performance against Motherwell. His work- rate was a lot better."
This has brought him zero goals in his last four appearances after netting within minutes of coming on as a sub for his debut against Hearts, then adding another in the home win over St Johnstone a week later.
Lennon has always insisted Pukki should not be considered a direct replacement for Gary Hooper, the club's top scorer for the three seasons he was at the Hoops before moving to Norwich in the summer.
He points out they have very different styles, but the Bhoys boss said of Pukki: "The goals will come, there is no question about that.
"He is still getting to know everyone here, but I am expecting big things from Teemu as the campaign wears on."
Lennon and his backroom staff are doing all they can to make the transition from a situation where Pukki was a sub more often than a starter with Schalke to a first-pick at Parkhead as painless and swift as possible.
The Finn has found the physical nature of the Scottish game a problem.
But Lennon explained he has not been alone in this and said: "He does need to strengthen up a bit and adapt to the British-style game.
"But these things take time. Look at Nir Biton, as well, and Amido Balde.
"I think they are going to be really good players for us once they start maturing and developing the way we want them to."