Cellino has been ordered to pay a fine of £502,000 for failing to pay duty on a yacht he imported from the United States.
The Italian entrepreneur's defence lawyer, Giovanni Cocco, announced that Cellino, who was not in court, planned to appeal against the court's ruling.
"This verdict is absolutely unjust and we will appeal," he told the Guardian after the brief court session.
Cellino agreed a deal to buy a 75 per cent stake in Leeds from Gulf Finance House Capital at the start of last month.
However, Tuesday's decision by the court in Sardinia could scupper the deal which was due to be considered by a Football League board meeting next month.
The governing body's 'owners and directors' test, prevents anyone with an unspent conviction for dishonesty offences from being a director, a 30 per cent owner, or from exercising control over one of its clubs which points to the Cellino takeover being blocked.
A Football League spokesman said: "The Football League has noted the outcome of the Court hearing earlier today regarding Massimo Cellino. We are engaged in an ongoing dialogue with his legal representatives in this country and cannot comment further at this time."
The Calgliari court ordered Cellino to pay a fine of 600,000 euros for failing to declare the imported yacht to the authorities and ordered the boat to be confiscated.
Cellino avoided paying 400,000 euros in import duty although the fine is far inferior to the figure of 1.165m euros demanded by the public prosecutor Andrea Massidda.
The 57-year-old already has a 2001 conviction for false accounting and is being investigated for alleged misuse of public funds relating to construction work on Cagliari's Quartu Sant'Elena stadium.
A Leeds spokesman said the club would not be commenting at this stage and were waiting for the Football League's decision on Cellino's proposed takeover before issuing a statement.