The Spanish are the reigning world and European champions and have only conceded one goal in the tournament so far.
"Brazil are favourites because they are playing at home," Iniesta said. "I don't know how many thousand people will be behind them.
"We must turn that into a form of motivation for us. There is no bigger challenge than beating Brazil at their home ground.
"Brazil are a great team and have played a spectacular championship so far, but we have a very good team too and I have no hesitation in saying that we are going for the title."
The final kicks off at 11pm tonight.