Anwar Hosseni, 24, caused £10,786 worth of damage to The Glade Of Light, a white marble “halo” bearing the names of all 22 people murdered in the May 2017 attack.
Hosseni scratched white lines across various parts of the memorial with a crystal Buddhist head figure in the early hours of February 9.
CCTV footage showed him praying and dancing at the city centre site which had opened to the public just weeks earlier.
Hosseni, of Twillbrook Drive, Salford, was arrested at his home address and told police his intention was to give “love, unity, honour and gratitude for the souls of those who passed away”.
Manchester Crown Court heard the defendant has an “established psychiatric history” including periods of detention under the Mental Health Act, with one post-dating the offence.
Gwen Henshaw, defending, said: “When interviewed he acknowledged that the memorial is not his property, he had no right to damage it.
“He now very much understands what he did was wrong and hurtful to many, including the victims’ families.
“He is mortified to know that he has caused them hurt and anguish because he prides himself on helping people. He is sorry for the pain that he has caused.”
Hosseni, who works as an actor and model “when he can”, pleaded guilty at an earlier hearing to criminal damage. He has no previous convictions.
Excerpts of several victim personal statements from families of the Arena victims were read out in court.
One statement said: “To know that someone has caused such damage in such a callous, nasty and pointless way breaks our hearts again”, while another said: “We have comfort in visiting the memorial and to learn it has been desecrated is beyond belief. How can someone stoop so low?”
Handing out a two-year community order, Judge Nicholas Dean QC, the Honorary Recorder of Manchester, told Hosseni: “The memorial is precious to the people of Manchester but especially precious to the relatives of the 22 who died.
“Your actions were bizarre. What you did was cause significant and widespread damage and of course that was interpreted by the relatives and friends of the victims as being a sacrilegious act in desecrating the memories of those involved.
“No doubt they would have thought there was some sort of political motive… I am satisfied that is not the case. You were motivated by some bizarre thought process. You thought you were somehow honouring the dead.
“If this had been a malicious, political act you would be facing a lengthy sentence of imprisonment.
“I accept what the doctors say, and what you say, in that you did not intend any ill will to the deceased or their families and friends. Quite the contrary, although the way you chose to express it would be difficult for anyone to understand.”
Hosseni also received a two-year criminal behaviour order which permits him from visiting the immediate area surrounding The Glade Of Light.
Last month the Duke and Duchess of Cambridge attended the official opening for the memorial ahead of the fifth anniversary of the attack committed by suicide bomber Salman Abedi, 22, at the end of an Ariana Grande concert.
The tribute is conceived as a living memorial – a peaceful garden space for remembrance and reflection, featuring plants which grow naturally in the UK countryside and have been selected to provide year-round colour and echo the changing seasons.
Around the anniversary every year, May 22, the white flowers of a hawthorn tree planted at its centre will bloom.