Kerem Akturkoglu's brace brought the Turkish side within a goal of levelling the knockout round playoff tie at the City Ground, but Callum Hudson-Odoi settled Forest's nerves with a goal in the 68th minute to seal a 4-2 aggregate win and a place in the round of 16.
With Forest just two points above the Premier League relegation zone, Pereira told reporters he had one eye on Sunday's match against Brighton.
"We were suffering a bit, but we are in the moment of the season where we need to think not about one game but about the next game," he told reporters.
"I decided to take this risk because I need to think about the Brighton game, it is very important for us. We need to go there with fuel and energy. My decisions were not just about this game."
Forest will either face FC Midtjylland or Real Betis in the next stage of the Europa League.
"We have ambition in the Europa League, it is to move forward to the next stage," said Pereira, who is Forest's fourth managerial appointment this season after Nuno Espirito Santo, Ange Postecoglou and Sean Dyche.
"We are not comfortable in the table in the Premier League and this is very important for us, to get the points to avoid a difficult situation."
Forest are 17th on 27 points, just two points ahead of West Ham United.