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 first "fight" with Brussels already loomed large on Monday in the British papers.
The front-page lead story in The Times reported that "Brussels forces Britain to accept Med migrants".
Migration is clearly a huge story, and a controversial one for the UK and Europe.
It has been for years, with an economic downturn and anti-immigrant political parties on the rise on the one hand, while at the same time television screens bring the horrors of a humanitarian crisis on our shores straight into our living rooms as we watch desperate people from the Middle East and Africa arriving, some dying, in their boatloads.
The European Commission, under new President Jean-Claude Juncker, says something decisive must be done.
He and his migration commissioner will on Wednesday unveil a migration strategy for the EU. Some parts are extremely controversial.
Included are two proposals strongly opposed by the UK, which says the migration crisis must be tackled by other means:
Now, the Cameron government wants to curb migration to the UK by EU citizens as part of his new deal with Brussels. So he certainly will not agree to increase the number of non-EU migrants to the UK.
And, as he has promised the UK to have "less Brussels" in daily life, he will oppose any migration quotas "imposed" by Brussels.
So actually this migration headline is less of a challenge and more of a gift for the new Cameron government.
It will be a chance to publicly bare its teeth at Brussels - the Home Office has put out a strongly worded statement about opposing Commission proposals to introduce non-voluntary migrant quotas - and to show some muscle-flexing to Eurosceptics, including in the Tory party itself, ahead of EU-UK renegotiations starting in earnest.
In fact, the Commission proposals are not new. They have been rejected in the past by UK Home Secretary Theresa May and quite a number of her European counterparts.
The Netherlands and Denmark will hear none of it.
France is nervous about the idea, with the anti-immigration National Front doing so well in the polls, and countries in Eastern and Central Europe, which house very few asylum seekers, do not want to start opening their doors now.
Estonia and Slovakia have already said "no" outright. Hungarian Prime Minister Viktor Orban described the migration quota plan as "mad" in a radio interview.
The migration strategy will be debated at a summit of EU leaders in Brussels next month and you can expect a heated argument.
It is not just the European Commission pushing the quota proposal.
In 2014:
In 2015 (1 Jan- 27 April):
source: UNHCR
Powerful Germany backs the plan - loudly - as the country that receives the lion share of asylum application in Europe- 200,000 last year alone. Berlin fears that number could double in 2015.
The Mediterranean frontline states of Greece, Italy and Malta are also in favour of refugee-sharing, for obvious reasons.
When it comes to home affairs issues like asylum, the UK has a so-called opt-in clause, which allows it to decide whether or not to adopt EU legislation.
So, whatever is eventually agreed on migration at EU level, it is hard to see how quotas could be forced on the UK.
The wreck of the Titanic is to come under the protection of the United Nations cultural agency Unesco.
[NEXT_CONCEPT]
The first days in office are challenging for any new government and this will certainly be a busy week for UK Prime Minister David Cameron - who, amongst other things, says he has already rolled up his sleeves to change the UK's relationship with Europe.