Fr Peter Slocombe, a parish priest at St Nicholas Roman Catholic parish in Winchcombe, was also found guilty of assaulting two police officers in an incident on the Rome subway on Monday.
The 72-year-old was told during a court hearing on Tuesday that he must spend his house arrest sentence at a Vatican training college in the Italian capital.
The Catholic clergyman, who was visiting the city while on holiday, must also pay £4,400 to each of the police officers.
Fr Slocombe denied sexual violence, resisting arrest and hurting police officers. His lawyer told The Times newspaper he will appeal.
The legal representative was quoted as saying: "He [Fr Slocombe] is shocked, because he did nothing and will appeal.
"The train was crowded, and he said he had his hands in his pockets all the time because he was afraid of pickpockets."
A court heard how Fr Slocombe repeatedly touched a female passenger who later exited a train and called the police.
Fr Slocombe then assaulted the officers when they tried to arrest him.
A spokesperson for Clifton Diocese told Premier: "We can confirm that Father Peter Slocombe was involved in an incident on the metro in Rome.
"We are not in a position to comment at present as we are dealing with the British Embassy to ascertain the exact details.
"Once we have all the details, we will issue a fuller statement."
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