Lombardi has been jailed for three years for a charge of violent disorder which he had pleaded guilty to at a pre-trial hearing.
Recorder of Preston Judge Mark Brown said: "There is no doubt in my mind that your purpose was to cause a violent clash with the Liverpool fans and that's demonstrated vividly in film footage.
"The footage shows that you had an active role and your assertion in evidence and in your basis of plea that you were just looking for signs for away supporter sections and were suddenly confronted by Liverpool fans is, in my judgement, nonsense."
Judge Brown said Lombardi's sentence would have been considerably longer if he had been convicted of the attack on Mr Cox.
But, he said: "Nonetheless, it is a feature of the case that during the violent disorder he was severely injured and that cannot be ignored.
"The violent disorder did not end with the attack on him because as he was lying unconscious on the ground it carried on regardless near to him and you, as is clear from the footage, were in the thick of it."
Alison Gurden, defending, said Lombardi was of previously good character and had played as a goalkeeper in the AS Roma academy between the ages of 13 and 16.
She said: "Mr Lombardi has a background of someone who, since he was a young man, has been very responsible and very hard working."
She said he had had a "huge maturity increase" after spending nearly six months in prison.
Judge Brown said footage showed Lombardi using his belt "as a whip".
He said: "Your actions and those of the other Roma supporters in the group are likely to have scarred the good name of football.
"In my judgment, you have brought disgrace on AS Roma supporters."
He added: "The game will probably be remembered not because of the football skill on the field or the result, but because of the awful tragedy Mr Cox endured and the violent disorder that took place outside the ground."
The court heard another man had been arrested in Rome in connection with the attack and was awaiting extradition.
Earlier: Roma fan cleared of inflicting grievous bodily harm on Sean Cox
Roma supporter Filippo Lombardi has been found not guilty of inflicting grievous bodily harm on Meath man Sean Cox.
The 21-year-old was acquitted of the charge at Preston Crown Court today in connection with the attack on 53-year-old Liverpool fan, Sean Cox, outside Anfield ahead of the Champions League semi-final on April 26.
The prosecution claimed he lashed out with his belt after another man knocked Mr Cox unconscious with a punch.
A jury of six men and six women found Filippo Lombardi not guilty after deliberating for just under nine hours.
About half a dozen members of Sean Cox's family, including his wife Martina, sat in the public gallery at Preston Crown Court as the verdict was announced.
Three members of Lombardi's family were also in court.
He will be sentenced for a separate charge of violent disorder, which he admitted before the trial.
Summing up the case, Recorder of Preston Judge Mark Brown said: "Football has been described as the beautiful game but the terrible events that took place outside Anfield stadium when Sean Cox was assaulted, and suffered catastrophic injuries, surely have blighted its reputation."
Mr Cox suffered a severe, traumatic brain injury in the attack and is still unable to talk or sit up unaided.
The court was told another man, referred to as N40, was responsible for the punch which knocked Mr Cox to the ground, causing his injuries, but the prosecution alleged Lombardi swung his belt towards Mr Cox as he fell and was jointly responsible for the attack.
The trial, which began last Thursday, heard Lombardi arrived at the ground after walking from Liverpool Lime Street train station with a group of 20 to 30 Roma supporters.
The jury was shown footage of the student appearing to swing his belt in the direction of Mr Cox, who was standing with his brother Martin, as he fell.
Martin Cox told the court he and his brother had been excited as they made their way to the ground.
However, he said he heard aggressive chanting from a group of people wearing dark clothes as they walked along Walton Breck Road shortly after 7pm.
He said: "I turned to Sean as if to say 'let's get out of here', or whatever.
"But as I turned Sean was lying on the ground."
Lombardi told the court he had been lost when he wandered on to Walton Breck Road, which was full of Liverpool fans, just after 7pm and had wrapped his belt round his hand because he feared he was walking into a "dangerous situation".
He said he had heard a man standing behind Martin Cox say something to him about a fight and had swung the belt at him to get him away.
He said he had not noticed Sean Cox until he saw him lying on the ground.