Old teammate, Lewis Hamilton, pushed hard for Mercedes team to sign e la Rosa
The 42-year-old Spaniard left his role as McLaren's respected test and reserve driver at the end of 2011 to return to the grid with HRT.
When HRT folded at the end of last season, de la Rosa was snapped up by Ferrari as the Maranello based team vows to develop the best driver simulator in F1.
"It's true," de la Rosa confirmed to Marca sports newspaper.
"Lewis has also confirmed it, otherwise I wouldn't say," he insisted. "I don't want to say any more, but I talked seriously about being at Mercedes.
"He was surprised and said 'It looks like we were too slow'," said de la Rosa.
"Otherwise it was more of the same; I had done it.
"Mercedes was attractive because the team is changing and it is a challenge, but McLaren would have been more of the same -- an organisation in which everything works already."
Asked which personal link - Fernando Alonso, Pat Fry or Santander's Emilio Botin - ultimately tipped the scales in Ferrari's favour, de la Rosa answered: "I don't know, honestly.
"I think you should ask them."