The Gunners have been heavily linked with the German World Cup winner as Mikel Arteta targets reinforcements at centre-back.
Arsenal have been unconvincing defensively this season and recently lost Calum Chambers to a long-term knee injury.
But Merson believes his former club would be better served targeting defenders with Premier League experience.
“I think Arsenal are getting a little bit carried away here,” he told Sky Sports.
“He’s playing at Bayern Munich where they’re getting 80% of the ball and they’ve probably got two [tough] games a season.
“This Arsenal team are not a 70-30% possession team anymore, it’s not a team that are dictating games. They need defenders now, people who can defend.
“They should be looking at the lads at Brighton, start looking at those players, when the ball comes in they’re going to head it out, kick it out, they put it in the stands. They need defenders.
“I used to think four or five years ago if there was a real good defender at Wolves or Brighton or places like that I used to think, ‘I’m not sure about that, Arsenal don’t play on the edge of the box, they play on the halfway line’. Not anymore, Arsenal don’t play on the halfway line anymore.
“It’s very rare you see them that high, they play quite deep now. When you’re 31, 32, 33, I give you one assurance – you ain’t getting quicker and this league is relentless, it’s ruthless, and it’s not the Bundesliga. It’s not playing for Bayern Munich, it’s playing for Arsenal and you’ll be playing a lot more.”
Arteta’s side, who sit 10th in the Premier League table after 21 games, take on Crystal Palace in Saturday’s early kick-off.