Referee Martin Atkinson handed Delph a straight red in the 49th minute of Villa's 0-0 draw with Sunderland, after the Englishman lunged in on Jordi Gomez.
The dismissal was Delph's first in his professional career, with the 25-year-old not even seeing yellow in 11 league appearances this term.
"I thought it was a harsh red card and we think three games is excessive," Villa coach Paul Lambert said.
"Fabian hasn't gone in maliciously at all. I can kind of understand why the referee's done it but I still think it's excessive."
Lambert added he feels Villa's treatment at the hands of referees in 2014-15 has been "unfair", claiming dismissals to Gabriel Agbonlahor (against Manchester United) and Christian Benteke (against Tottenham) were also questionable.
"I think it's been unfair at times," he said.
"I think because we are a youngish kind of side, we can be a target for that.
"Even when you ask the lads about it sometimes they can't believe it either. It's just something you have to try and get through.
"You just have to try and keep 11 guys on the pitch but I saw some challenges over the weekend on TV and they weren't punished with anything. You think to yourself 'how is that different from ours?'
"I think if you go back to Gabby's red card, everyone knew that shouldn't have been sent off.
"So we were down to 10 men against Manchester United then they told us that Gabby shouldn't have been sent off - well thanks very much.
"Christian's red card I would also debate, too."
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