The Spanish giants went through on away goals following the 1-1 draw in the Camp Nou and Iniesta said that it was "normal" for teams to find it hard going at this stage of the tournament.
"It's true that PSG are a fantastic team – really excellent," UEFA.com quotes Iniesta as saying. "They have players who have lots of experience. They have players of the highest level, who are technically very good.
"We knew this was going to be hard and it's true that we had to endure a bit to get through. However, that's completely normal against a team which is as strong as PSG in a quarter-final of the Champions League.
"The suffering and the tension were high right to the end but we achieved what we set out to do. Maybe we should have controlled the game more to avoid suffering too much... but big games are like that and we got the result that we needed."
The draw for the semi-finals takes place on Friday.