The ASA agreed with a complaint that the imagery trivialised the decision to take out a loan and ruled the advert must not appear again in its current form.
The firm defended its decision to use cartoon pigs because the image was based on a piggy bank, which is associated with saving.
The ASA said: “We noted that the ad featured brightly coloured images of smiling cartoon pigs at the top of each page including one pig that appeared to have glistening gold coins coming out of its back.
“Although we acknowledged that consumers were likely to understand piggy banks to be associated with frugal financial planning, in the context of promoting a short-term loan and in light of the fact that the piggy bank appeared to be spilling its contents, we did not consider this connotation to be clear or relevant.”
The ASA said the cartoon gave the general impression that the service offered was one that could be approached in a light-hearted manner.
The broker also came under fire for suggesting a payday loan could be used to “treat yourself and a loved one to a weekend away and a slap up meal”.
Payday Pig said it was pointing out that a payday loan could be used for positive events not just negative experiences.
Stop Go Networks, the parent company of Payday Pig, said it was never its intention to trivialise the decision to take out a loan or to encourage frivolous spending.
It said its website contained significantly more than the prescribed warnings required about the need to pay back short-term debt on time and that payday loans were not intended for anything other than short-term borrowing.
But it said that it did not want the message to be misconstrued and would remove the sentence from the website.
The ASA ruled that for most consumers going out for a meal or for a weekend away would not be essential or urgent, therefore the reference to using high interest, short-term credit to fund such activities was likely to be seen as encouraging frivolous spending.