The pair shared a fractious relationship at the team, where they duelled for the 2010 title before German Vettel began his four-title winning streak.
This year, after the 'Multi-21' team orders affair, 37-year-old Australian Webber decided to leave F1 and join Porsche's new Le Mans foray for 2014, despite interest from other Grand Prix teams.
"Teams like Lotus and Ferrari - and even Red Bull to a degree, once they couldn't get Kimi (Raikkonen) - were on the radar so to speak," Webber told BT Sport.
But he admits that the Vettel factor ultimately coloured his decision to quit altogether.
"The future has been Sebastian, they want to keep him happy as much as they can, and things come onto the radar and you think 'this is probably not how I would like it', so it does go into the decision," said Webber.