Celtic have had three bids rejected for the 25-year-old including one at half time during Posh's 2-0 win against Crawley Town on Saturday.
"I'm not angry at Celtic, I'm just stating the facts and people can make their own minds up about what's gone on," Ferguson told the Peterborough Telegraph.
"The first bid they made was a waste of time anyway. They can't have watched him much over the past few years if that's all they think it's worth."
Scottish clubs must complete any transfers by 11pm on Saturday, whereas the London Road outfit have until the same time on Monday evening to finalise deals.