The design was inspired by the fireworks of Belgium's famous music festival Tomorrowland and stands for diversity, equality and inclusivity.
However, Belgium spokesperson Stefan Van Loock said FIFA was rejecting the shirt not because of the colours, which are typically linked to LGBTQ+, but because of the commercial link to Tomorrowland.
The festival's logo is incorporated in the "o" of "Love".
Belgium's warm-up shirt was also rejected by FIFA because of its references to Tomorrowland, he said.
FIFA is allowing Belgium to play with the away shirts if the word "Love" on the etiquette is taped over but Van Loock said the Red Devils will play the first three games in their main red shirt regardless.
The away shirts are a new design and were introduced in September. Since then, Belgium played in them in several UEFA Nations League games.
The rejection comes after FIFA threatened to issue yellow cards to any player wearing the multi-coloured 'OneLove' armband which was introduced to support diversity and inclusion.
The Belgian Football Association said earlier on Monday that its captain Eden Hazard will not play wearing the armband.
