The 29-year-old did not feature in Cardiff's 3-1 defeat to Brighton on Wednesday and later made his feelings known via his Twitter account.
"Does anyone need a gardener? Looking for work," commented Parkin.
The player has since apologised to manager Malky Mackay, who has included him in Cardiff's squad for their match at Burnley on Saturday.
"Everybody's disappointed when they're not playing and I would be as well. If you're not, then I'm querying why you're not," said Mackay.
"He's frustrated that he wasn't playing but I get why that would be the case.
"He's come to see me about that just to say 'I was tweeting a mate and it wasn't any sort of public outcry.'"
Parkin moved to Cardiff from Preston North End in January but has found first-team opportunities hard to come by as he has only started three matches for the Welsh club.