The former Toro Rosso driver was linked to teams including Force India during last year's driver market speculation, but announced on Saturday that his hopes now seemed dashed.
"I never imagined that after Red Bull's incomprehensible decision not to count on me in 2012, having done my best sporting season in F1 [in 2011], I would have to fight so much outside the track before finally assuming that in 2013 I will not be in F1," he said.
"I assure everyone that I have been convinced for most of the 2012 F1 season that my seat was secured in a team that usually scores.
"So they did tell me and I believed it to be true.
"Due to this conviction I passed up other opportunities in other championships.
"Those who committed themselves with me have given me reasons that I must accept but that I do not share.
"F1 has become an auction."
Alguersuari, who was also a candidate for the BMW DTM seat that ultimately went to Timo Glock, will continue with Pirelli's test programme in the hope of a 2014 F1 chance.
"Is my career over in F1 at 22 years old? Despite everything, I strongly don't think so," he said.
"So I will continue to be active in Formula 1 [with Pirelli], and complete more kilometers than any third driver in this discipline.
"I know how old I am, I know my track record and I'm convinced that I deserve a winning car in F1. And I will keep fighting for it."
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