The Catalan outfit lost their last group match to Paris Saint-Germain, placing more importance on the clash with the Dutch outfit.
"Ajax are a team like us that enjoys having a lot of the ball, so I'm sure that will require us to be very focused," Iniesta told La 1.
"Their boss [Frank de Boer] was also a stylish player and in that sense I think he has put his stamp on the team.
"The defeat in Paris obliges us all the more to try and get a win."
Barca also faced Ajax in the group stages last season – winning 4-0 at the Camp Nou.