The Blues' acting chairman, Peter Pannu, spent the day talking to lawyers and the club are going to demand £5million in compensation.
The contact from Villa was not an official approach, but it can be disclosed that an email was sent to Birmingham seeking clarification about McLeish's status.
McLeish announced his resignation via an email on Sunday and the Scot was immediately linked with a move to the vacant manager's post at Villa Park.
Peter Pannu has spent the day speaking to lawyers about McLeish's shock move, while former Villa boss Graham Taylor has questioned his old club's approach to finding a new manager.
Pannu said: "He is still our contracted staff and Birmingham City FC does not grant him any right to speak to any outsiders until the matter is resolved. It's about time discipline is instilled into this game and I am not a person who gets pushed about."
Meanwhile Taylor, twice manager of Villa in the past, criticised his former club for the way they have gone about seeking a replacement for Gerard Houllier, who stepped down due to illness.
Taylor told BBC Sport: "It just doesn't appear to have been thought through and for the first time the ownership of the club is coming under severe criticism.
"When Gerard became ill, it must have occurred to them that he may not come back, even if the signs were that he may have returned.
"This is not being disrespectful to Gerard in any way, but once he became unwell then you have to immediately start exploring what you might do if he does not come back.
"It doesn't appear to me and many others that this has been done. They seem to be going from name to name.
"Villa don't seem to have grasped that nettle at all. It is disappointing. I still live in the area and have a special feeling for them as you always do about clubs you have managed, but I have been surprised and disappointed at their handling of this."
Taylor also believes McLeish is tough enough to deal with potential opposition from Villa fans and anger from Blues supporters.
He added: "I think Alex has the strength of character but it won't be easy for him. He has a hardness about him.
"It would be difficult though, because many Villa fans would not want a Birmingham man as their manager and many Birmingham supporters might see him as a traitor. He is a strong man though, and I think he could cope with that."
Within 24 hours of McLeish's announcement, nearly 6,000 people signed up to a Facebook page entitled 'Aston Villa Supporters - We don't want Alex McLeish'.