The two biggest clubs in Spanish football go head-to-head in Madrid with Barcelona looking for a Clasico win to keep their title push alive.
The Catalan giants sit four points behind leaders Real in La Liga and know defeat could spell the end of their title defence.
"We know that we are always required to bring our very best football when we play at the Bernabeu," Iniesta told a news conference on Thursday.
"But we have to be, more than ever, Barca.
"We just have to be brave, keep possession. If we don't do that, we will have a bad time. It's a ground where the biggest demands are made of players.
"We have to go out and play to win and be daring. Things have normally worked out well when we have been daring."
At suggestions Barcelona fans would feel like underdogs heading into the match, Iniesta said they had every right to be confident.
"I don't like to think that there are supporters of our team that don't think we are able to win the league or win at the Bernabeu," he added.
"This is a team that has won so many different things. We have won the right to believe in ourselves.
"Yes, we have had bad games, but so have every team. Generally year after year we have been winning with this team.
"Big demands have been made of this team and we have responded and we have been winning well.
"If things don't go well it is normal that there will be criticism, but to think that Madrid are just going to beat us easily, I don't think anyone should think that.
"We are going there to play a good game."
Of Barcelona's title bid, Iniesta also said: "It's not as if we are 20 points from the leaders. We still have a chance of catching up. It's not that hard."
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