Messi netted the 24th hat-trick of his Barcelona career as Gerardo Martino's men swept past the Dutch champions in confident fashion at Camp Nou on Wednesday, with defender Gerard Pique also finding the net.
However, Barca survived a number of scares on their way to victory, Ricardo van Rhijn and Lerin Duarte each going close for Frank de Boer's men, who missed a chance for a late consolation as Kolbeinn Sigthorsson saw his penalty saved by Victor Valdes.
Ajax's positive attacking play forced Barca to play on the counter-attack for large periods of the game, but Messi believes the ends more than justified the means.
"It is good to make a winning start knowing that all groups of the Champions League are difficult," he told Canal +.
"As the games pass we will adapt further. In the second half we did so as we always had the ball. We had a great game.
"There are games when it is better to have the ball and others in which the rival presses and you need to get out on the counter. We have the good players and the super-fast players to do so."
Messi was also quick to offer his support to Martino, who took his place on the sidelines just days after the death of his father.
"I was sorry to hear about his father. We are here to give our support," Messi added.
Barcelona's next Champions League clash takes place at the start of when the Spanish champions travel to Parkhead to face Celtic, who beat the Catalan club in the same fixture last season.
