The Metropolitan police announced on Sunday morning that 15 people were arrested during the protest near Downing Street.
Twelve people were arrested on suspicion of violent disorder and three for assault on police.
A police statement said the youngest arrest was a 16-year-old boy.
Of the 15 people arrested, 14 have been bailed to return to London police stations in early July.
A 24-year-old man remains in custody having been arrested on suspicion of assault on police.
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