The Spain international says the Catalans are balanced and feature the best player in the world in Argentine attacker Lionel Messi and are a worry for Bayern Munich.
The Bavarians are widely regarded as the top-form side in world football, having wrapped up the Bundesliga title with a record six rounds to spare and stormed into the last four of the game's premiere club tournament with a resounding 4-0 aggregate win over Italian champions Juventus.
Martinez, speaking ahead of Tuesday's first-leg clash with Barca at the Allianz Arena, is extremely wary of the threat posed by the Blaugrana to Bayern's hopes of atoning for defeat by Chelsea in last year's Champions League final, though.
"Unfortunately, everything about them worries me," Martinez told AS. "They're a very balanced outfit and they have the best player in the world.
"And even if [Lionel] Messi has a bad day, he has plenty of teammates who can do a very good job, such as Pedro, Alexis [Sanchez], [David] Villa, Xavi, [Andres] Iniesta, etc."
Indeed, Martinez believes there is virtually nothing to choose between these two genuine European superpowers.
"I think it's the perfect moment for us to take on Barca," the former Athletic Bilbao man claimed. "The problem is that they're also in good form!"
Still, Martinez, who joined Bayern from Bilbao last summer for a reported fee of 40 million euros, is looking forward to the challenge, particularly from a personal perspective, as he is keen to pit his wits against the player he believes to be the best in his position.
"Sergio Busquets is the key cog in the Barca machine," Martinez said. "There are other players who grab the headlines, but if this Barca side has won so many titles it's thanks to him.
"He always holds his position. He brings other players to life, such as Xavi or Iniesta. They can join in the attack knowing that he's got them covered."