Niki Lauda, Mercedes' chairman and shareholder, backpedalled this week after hinting he might have approached Red Bull's reigning triple world champion.
But Surer is quoted by Speed Week: "If you want to be a top team, you have to try to weaken your opponent.
"This way (signing Vettel), you would weaken your rival and strengthen yourself at the same time.
"It's completely normal if Niki Lauda is trying to get Vettel," added Surer.
It is likely Lauda backpedalled on his public approach to Vettel due to the signal it sends to Mercedes' existing drivers, comprising Nico Rosberg alongside Lewis Hamilton.
"Of course it's unpleasant as a driver if you know your team is looking for alternatives, and if you look at the contractual situation, then that is Rosberg," said Surer.