"I am deeply moved by the death of little Alfie", he posted on Twitter.
Although Italian officials earlier this week granted Alfie citizenship and a Vatican-linked hospital offered to take the toddler for further diagnosis and treatment, United Kingdom courts repeatedly refused to allow the transfer, ruling that it is not in the child's best interest. He had been in a semi-vegetative state for more than a year.
Court of Appeal judges upheld his decision, while Supreme Court justices and European Court of Human Rights judges refused to intervene.
After a series of court cases, doctors at Alder Hey Children's Hospital in Liverpool removed his life support on Monday, against his parents wishes.
In a statement, Alder Hey Children's Hospital said: "We wish to express our heartfelt sympathy and condolences to Alfie's family at this extremely distressing time".More news: With Heat Season Over, Hassan Whiteside Again Vents About Playing Time
As part of commemorating the life of Alfie, thousands of people gathered this evening to set off blue balloons with messages to Alfie, creating a attractive display in the sky near to the hospital where Alfie sadly died. His case drew the support of the Italian government, which granted him citizenship, and the Vatican's Bambino Gesù hospital offered to care for him. It also prohibited his parents from seeking treatment elsewhere.
CBN News spoke with Andrea Williams, the chief executive of the Christian Legal Centre, which is representing Alfie's father, about the toddler's death.
The rulings echoed another high-profile case, that of Charlie Gard, the British infant who had a rare genetic abnormality known as mitochondrial DNA depletion syndrome.
"We would now ask you all to return back to your everyday lives and allow myself, Kate and Alder Hey to form a relationship, build a bridge and walk across it".
Charlie's parents fought a long and public battle to prolong his life, but bowed to the consensus of medical experts who said there was no realistic chance of saving him: The child had irreversible brain damage.
In an earlier statement published on April 12, Alfie's mother Kate James wrote, "How sad is it that someone can tell you where and when your child is going to die?" Fly high little man; and Alfie you stole the heart of the world! Nobody could have fought a tougher battle for Alfie.