Eurovision rules say the public broadcasting network of the home country of the winning musical act must host the next year's event.
Soler was quoted by ABC Punto Radio as saying "If we won, I think it would be impossible to stage the next edition because it costs so much money."
Britain's Sky News reported directors from Spain's public broadcaster, TVE, sent her a joke message reading, "Please don't win!"
Soler told the BBC Friday she was misquoted by a "very bad" journalist and she was never advised to underperform.
"Yesterday was a difficult day for me because I had an interview with a journalist that was trying to get words that I didn't say. The public Spanish television is with me and is supportive of me, since the beginning of the day until now. … It will be wonderful news for Spain and the people in Spain," Soler said at a press conference in Azerbaijan, where the Eurovision contest is being held.
Soler, who will perform "Quedate Conmigo" ("Stay With Me"), advanced to the final 26 nations competing in Saturday's live event in Baku.
Spain has won the Eurovision contest twice, in 1968 and 1969, Sky News reported.
Oddsmakers have Sweden's entry, Loreen, the favorite to win this year's contest.