Yes, Dario Nardella did make a tweet along those lines.
The Global News tweet you linked reads:
The mayor of Florence, Italy, @DarioNardella
initiated "hug a Chinese" on Twitter on Feb 1, opposing anger toward China amid the #nCoV2019 outbreak, and calling for "Unity in this common battle!" Many Italian netizens responded by posting photos of themselves with Chinese.
The tweet in question is this one, from February 1st:
.#coronavirus: seguiamo le indicazioni delle autorità sanitarie e usiamo cautela, ma nessun terrorismo psicologico e soprattutto basta con i soliti sciacalli che non vedevano l’ora di usare questa scusa per odiare e insultare. Uniti in questa battaglia comune! #AbbracciaUnCinese
The hashtag translates to #HugAChinese.
Note that the first cases of coronavirus in Italy were only confirmed a day before, on January 31st, and the number of confirmed cases only really took off at the end of February.