The Argentine spoke of how difficult it is to play against teams that play a deep defensive line, as his side struggled to break down their opposition at Camp Nou
Cristian Tello had made it 1-0 early on in the match, before a Dani Alves own goal levelled the scoreline at the break.
Spartak then took a 2-1 lead on the hour mark courtesy of a well-taken finish from Brazilian midfielder Romulo, but Messi's second-half contribution proved decisive in the match, as he scored twice to win the game.
"It's not easy to win a game like that when the other team sits back and defends," Messi told Uefa.com
"They have very fast forwards and played well on the counterattack."
Messi also expressed his sadness at the injury Gerard Pique picked up in the 12th minute, but stressed there were players capable of covering for the Spain international.
"It's a shame about [Gerard] Pique's injury. He is important for us, just like Carles Puyol is, but we have plenty of players in the squad, plus the reserves," he added.
Pique himself sent a message on Twitter following the final whistle, displaying his happiness at the result, and saying his injury was not as serious as first feared.
He said: "Great comeback from the team! It's really important to start winning! Thanks to all of you for the support. I hope to be playing again soon."
Barcelona sit top of Group G following their win tonight, as Celtic drew 0-0 with Benfica in the other group game.