Discussion of a draft law to be submitted to parliament to amend Article 227 should be a "priority" pending a review of "all articles concerning the fight against violence targeting women", Chahed told Mosaique FM radio.
"Our country can no longer refer to laws that are old fashioned and which do not reflect the spirit of rights and liberties," said the 41-year-old prime minister.
Chahed's comments come two weeks after a Tunisian court approved the marriage of a 13-year-old girl to a relative who made her pregnant, under the terms of Article 227.
The ruling infuriated non-governmental organisations who said the girl was raped.
Article 227 states that a man who has sex with a girl under 15 years old without the use of force can be sentenced to a six-year jail term but proceedings against him would be halted if he marries his victim.
Dozens of people staged a protest outside parliament last week, denouncing the article as a "backward" piece of legislation that should be revoked.
Chahed, whose country is viewed as being ahead of most Arab countries on women's rights, said on Friday that 2017 "will be the year of the child" in Tunisia.
He said he will strive to draw up a strategy to improve the lives of children in Tunisia, particularly in the field of education.
A bill to counter violence against women was drafted in Tunisia in 2014 but is still waiting to be discussed in parliament.
Activists argue it is up to social movements to bring about "real change" in government legislation.
"It is the Tunisian society and active NGOs that are forcing the government into revising Article 227 today," lawyer and human rights activist Ghazy Murabit told The New Arab.
"It is this social activism that will push parliament towards making a real change," Murabit said.
"Unfortunately lawmakers in Tunisia too distracted by party politics to get the ball rolling on some real change in constitutional humanitarian rights," he said.
"Bringing about legislative change through social activism is the real essence of democracy."