The Spanish champions were knocked out of the Champions League at the quarter-final stage by Atletico Madrid last week, before losing 1-0 to Granada in La Liga at the weekend.
However, Iniesta is confident that his side will return to form in the Copa del Rey final against Real Madrid on Wednesday evening.
"When things don't go to plan, you get upset, cry, suffer and then pick yourself up," he told reporters at a press conference.
"A lot of times we've got it right on the big occasion. We're the first to be critical of ourselves. We're not shirking our responsibility, but sometimes things don't turn out the way you want."
Barcelona are currently four points off the pace in La Liga.