The agency says more than 700 divers have visited the site, 4,000m under water off the coast of Canada.
The ship will fall under the 2001 Convention on the Protection of Underwater Cultural Heritage once it passes the 100th anniversary of its sinking on 15 April.
The convention aims to prevent unscientific or unethical exploration.
Irina Bokova, director-general of Unesco, said the sinking of the Titanic was "anchored in the memory of humanity" and it was important to protect the site where 1,500 people lost their lives.
"There are thousands of other shipwrecks that need safeguarding as well... We do not tolerate the plundering of cultural sites on land, and the same should be true for our sunken heritage," she added.
The 2001 convention only protects vessels that sank more than a century ago.
The Titanic, built in Belfast, sank on its maiden voyage after setting off from the British port of Southampton.
It hit an iceberg off the coast of Newfoundland in Canada en route to New York, sinking two-and-a-half hours later.
The wreck of the Titanic is to come under the protection of the United Nations cultural agency Unesco.