Lamela arrived at White Hart Lane for a club-record fee, believed to be around £30million, but he has been a bit-part player this season and has not started a Premier League match.
Villas-Boas believes much of this is down to the language barrier.
The Argentina international, 21, was an unused substitute in Sunday's 1-0 win over Hull City and the former River Plate forward has had to make do with looking to have an impact in Europa League ties.
He is yet to score his first goal for the club and, with limited game time, the summer signing has not had the immediate impact many supporters would have expected.
But when asked if the fee paid for Lamela meant there was pressure to pick him, Villas-Boas replied: "Not really, no.
"We have been speaking a lot with him. I think getting acquainted to the Premier League is important but he doesn't know the language.
"(Roberto) Soldado had some knowledge of the language before (he came) so it was a little bit easier for him.
"With Erik it was a little bit more difficult but we have given him massive, massive help and his family arrived this week," he added.
"He knows he isn't producing half of what he can produce but he understands the situation now is that he has to compete for his place."