Senior Labour figures were criticised in a backlash by members after a ditched attempt to topple leader Richard Leonard.
MSP Jackie Baillie and MP Ian Murray were named by youth representatives on the ruling SEC body angry at bitter split in the troubled party.
Leonard faced demands to quit in a series of damaging resignations from his front bench, but nobody stood forward to take the position and the attempt failed.
A motion of no confidence in Leonard, submitted by four Labour MSPs, was withdrawn on Saturday. Leonard said it's now time to end "internal plotting" and called for "unity".
In a post on social media, members of Scottish Young Labour claimed: "It is worth saying that colleagues whom we deeply like and respect did speak in favour of the motion, and their anguish and good faith was plain to see.
"This was the exception rather than the rule though. In particular, the actions of Jackie Baillie MSP and Ian Murray MP were completely shameful.
"By speaking so strongly in favour of the motion of no confidence, they have handed our opponents a crutch to beat Labour with in future elections, and will have damaged relations between the UK and Scottish Labour parties."
Baillie and Murray declined to comment on the claim.
