The racially aggrevated damage was reported around 2.50 am this morning
No arrests have been made and enquiries are ongoing.
GMP will be working alongside Manchester City Council and the artist to ensure this graffiti is removed and the mural is repaired as soon as possible.
Chief Superintendent Paul Savill, of GMP’s City of Manchester division, said: “This is disgraceful behaviour and will absolutely not be tolerated.
“Greater Manchester prides itself on being made up from a number of diverse communities and hate crime in any form is completely unacceptable and not welcome here in our city.
“GMP takes crimes of this nature very seriously and an investigation has been launched. If anyone has any information that could help us to identify this offender please do not hesitate to speak to police.”