Guardiola, 45, won 14 trophies in four years, before leaving Barca in 2012.
City have four points in Champions League Group C, two fewer than Barca, who eliminated them in the knockout stages in both 2014 and 2015.
“They play very attractive football,” said Enrique, 46. “We know it will be more difficult than previous seasons.”
Guardiola left Bayern Munich during the summer to take charge at Etihad Stadium, and Enrique insists “you can see the hands of Guardiola” in City’s recent displays.
They have won six of their opening eight Premier League matches to top the table ahead of Arsenal.
City were beaten in the semi-finals by eventual winners Real Madrid last season, and Guardiola feels more long runs in the competition would show progress.
“I need to know my team as quick as possible and tomorrow is a good test,” said Guardiola.
“You are important in Europe when you are there a lot of the time – that is the next target.”
City goalkeeper Claudio Bravo and forward Nolito are expected to feature at the Nou Camp but midfielder Yaya Toure, another former Barcelona player, is not in Guardiola’s 21-man squad.
Forward Kevin de Bruyne is fit again, while club captain Vincent Kompany came off the bench against Everton on Saturday to make his second appearance of the season.
Barca have not lost at home in 17 Champions League matches, and welcomed Lionel Messi back from a groin injury in Saturday’s 4-0 win over Deportivo La Coruna.
Asked what advice he can give defenders to deal with Messi, Guardiola said: “I don’t know. It is so difficult to control the talent, we know that. It’s a good test for us to compete at one of the best teams.”
Enrique said defenders Jordi Alba and Sergi Roberto had both overcome injuries and were in contention.