Fresh concerns over Liverpool's World Heritage status
Developments including Everton's new football stadium could threaten the "authenticity and integrity" of Liverpool's waterfront, Unesco said.
The organisation said the city was failing to address concerns about overdevelopment.
Unesco warned it could lose its World Heritage status in 2020 unless leaders provided assurances about their plans.
Liverpool City Council said it could preserve the area's character while carrying out regeneration.
The city's World Heritage status, obtained in 2004, was inspired by its maritime past and covers six areas, including the Pier Head, Ropewalks and William Brown Street.
Unesco added Liverpool to a list of sites at risk of losing the status in 2012 following concerns about the impact of tall buildings at the proposed £5bn Liverpool Waters regeneration plan.
In its latest report - due to be considered at an annual review of at-risk sites next week - Unesco has said it was "regrettable" the council had ignored previous recommendations against building a stadium at Bramley Moor dock.
The city risked "systemically excluding heritage concerns and conservation outcomes", it said.
Everton hope to begin work on a new ground at Bramley Moore Dock in 2020 and is set to launch the next phase of a public consultation.
Unesco also said it had only received limited assurances that Liverpool Waters would not detract from the site's character.
Developer Peel has said the development will not go ahead in its original form.
The council has been asked to respond to Unesco's concerns by February.
Mayor Joe Anderson said the council would launch a World Heritage Trust and a planning framework that would help it maintain Unesco status.
He added: "Our situation is complex because the city centre is not a monument - we are a bustling, dynamic, thriving 21st century city that continues to evolve.
"It is disappointing that the report seems to underestimate what progress is being made."
Bill Addy, chairman of the Liverpool Visitor Economy Network, said Everton's plan to redevelop Bramley Moore Dock would "breathe new life" into a neglected area.
He added: "Developments along the north docks will create thousands of jobs for local people and could bring millions more visitors to the city."