The 31-year-old is still without a club after being released by Bristol Rovers over a year ago and has been training with Alloa and Morton. He was linked with a move to the Belgian second division side, who are now managed by former Chelsea star Jimmy Floyd Hasselbaink.
But the three-times capped former Hibs and Celtic player has been told he isn’t wanted by Antwerp.
Royal Antwerp chairman Gunther Hofmans said: “First and foremost, we have six strikers at the club already and we are not intending to lose any of them. Additionally, Riordan appears to be something of an enfant terrible and has the disadvantage of not having played any league football for over a year.
“We don’t take such risks with only 12 games left for us.
“If we bring a player in, he must be immediately employable.”
Riordan – who is the third all-time top scorer in the SPL – has also had spells at Shaanxi Chan-Ba in China and St Johnstone.