Protesters tried to break through a police cordon while the premier’s arrival at Palazzoli Spa, an electrical appliances company, was met with boos, Il Fatto Quotidiano reported.
The protesters included students and members of the Fiom-CGIL trade union, who gathered to protest against Renzi’s controversial “Jobs Act”.
A group of factory workers put on “forced leave” by Palazzoli Spa were also among the protesters.
Renzi called on Italians to have faith in his Jobs Act, which he has pledged will reboot Italy's economy and lure in foreign investors.
But he has clashed with the unions over plans to make it easier for companies to fire people.
The debate centres on the future of Article 18, a law which currently protects those who are unfairly dismissed. The premier argues that Article 18 - drawn up in 1970 - is hampering efforts to get the recession-hit economy back on track.
Renzi also addressed justice and tax reforms during his speech.
"We need to restore dignity to the country,” he was quoted in Il Fatto as saying.
“We need a simple state, that makes things easier. The country needs tax simplification.”
Protesters from across Italy also descended on Rome in late October for a vast rally, organised by CGIL, against the labour measures.