Barca trail leaders Real Madrid by just one point, but the team has at times faced criticism for their performances under head coach Luis Enrique this term.
However, Wednesday's 1-0 victory over Spanish champions Atletico Madrid in the Copa del Rey quarter-final first leg at Camp Nou was Barca's fifth consecutive win in all competitions.
And midfielder Iniesta is confident that Barca will continue to improve.
"I always like to think that the best has yet to come," he told the club's official website. "There is a long season left for us to do things well."
Iniesta felt Barca deserved their triumph over Atleti, secured by Lionel Messi's 85th-minute winner, but is aware there is still plenty to do in next week's return leg.
"We are very happy to have won a game against a very difficult opponent," he added. "1-0 was a fair result and we're happy with it.
"Not letting in any goals was huge, but that doesn't guarantee anything. There is still the return leg to play and we'll have to try to get things right.
"Atletico are always hard to play against. They do things very well and don't allow many chances.
"But we played well, created danger and looked to outnumber them in the right parts of the field."
