The report resulted from a department review of policy on obtaining information or records from journalists in criminal and civil investigations.
President Barack Obama ordered the review in May.
The report emphasized "it has been and remains the Department's policy that members of the news media will not be subject to prosecution based solely on newsgathering activities."
"Furthermore, in light of the importance of the constitutionally protected newsgathering process, the Department views the use of tools to seek evidence from or involving the news media as an extraordinary measure," the report said.
The department would use such tools "only as a last resort, after all reasonable alternative investigative steps have been taken, and when the information sought is essential to a successful investigation or prosecution."
"The Department of Justice is firmly committed to ensuring our nation's security, and protecting the American people, while at the same time safeguarding the freedom of the press," Holder said in a statement Friday. "These revised guidelines will help ensure the proper balance is struck when pursuing investigations into unauthorized disclosures."
Holder said in addition to the reforms, Congress should enact media shield legislation.
"I look forward to working with leaders from both parties to achieve this goal, and am grateful to all of the journalists, free speech advocates, experts, and Administration leaders who have come together in recent weeks -- in good faith, and with mutual respect -- to guide and inform the changes we announce today."