The winger - a record signing from Roma at the beginning of last season - struggled to settle during his first Premier League campaign, making just three top-flight starts for the White Hart Lane club.
However, Pochettino believes patience is needed as Lamela adapts to his third manager since arriving in north London.
"Everyone expects a big performance from Erik Lamela," he said. "He needs time.
"I expect from all, not only from Lamela, to show their ability."
Tottenham have brought in Ben Davies and Michel Vorm from Swansea City, together with Eric Dier from Sporting, during the close season, but Pochettino would not be drawn on whether there were any more players on his radar.
"I won't talk about another player or our targets," he continued. "Ben Davies, Michel Vorm and Eric Dier add balance to the squad. The profile they have is good for us."
And, while acknowledging he has taken charge of one of the biggest teams in the Premier League, Pochettino stressed it was "impossible" to promise success.
"I think the challenge for all managers is to win trophies, but I'm focused on developing our style at Tottenham - that's the most important at the moment," he added.
"It's important to work hard, to believe, to be realistic. We are ambitious but it's impossible to promise (trophies). We need to show our ambition in every game."
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