The sport said Mercedes sees the reigning world champion as a potential new teammate for fellow German Nico Rosberg beyond 2015, after Lewis Hamilton's current contract expires.
And Red Bull's Dr Helmut Marko, who has Vettel under contract until the end of next year, said McLaren has made the four-time title winner an "outrageously" high offer.
"Of course they target him," Marko added.
Fascinatingly, Mercedes' Toto Wolff did not deny the German marque might be interested in Vettel.
"This world is too competitive to want to go into our plans in the public," he said.
"We are talking about a handful of top drivers. All the best teams fight over them.
"We try to build a picture of how the market moves until we come to our decisions," Wolff added.