The young protester, who had been hospitalized with serious injuries since then, died early on Wednesday.
Some reports suggest that she was not participating in the protest and that she was a passerby when regime troops attacked protesters.
Bahraini officials have denied reports blaming security forces for her death, saying that the iron rod was hurled by a vandal. Rights activists, however, say they have a video showing security forces carrying rods during the crackdown in Daih.
Since the beginning of anti-government protests in Bahrain, dozens of protesters have been killed and many others have been wounded in the Saudi-backed crackdown.
Bahraini authorities have also detained hundreds of activists and sacked thousands of public sector workers for supporting anti-regime protests.
Bahrainis have been holding street protests demanding an end to the rule of Al Khalifa dynasty since mid-February. Peaceful demonstrators are attacked with live rounds and tear gas.
On November 23, the Bahrain Independent Commission of Inquiry, set up to investigate reports of rights abuse during the crackdown, announced that the regime had used ''excessive force'' to crush the uprising.