Leo Seelig, prosecuting, told the court that the Crown Prosecution Service would be arguing that the four men should be sentenced on the basis that the arson attack was related to terrorism.
Mrs Justice Cheema Grubb said she would not rule on the question of terrorism at this stage – with defence counsel arguing that there was no evidence for such a connection.
The judge said that the four would be sentenced following the outcome a trial of a fifth man, Subhan Ahmed, who has denied assisting an offender.
Iqbal and Khan, of Leyton, Atshatshi, of Dagenham, and Ali, of Walthamstow, were remanded into custody.
Run by volunteers, Hatzola has served the north London community of Golders Green, which has a large Jewish population, since 1979.
Hatzola, the Hebrew word for save or rescue, is a large non-profit, Jewish-led organisation that provides a free emergency medical response and transportation to hospitals regardless of faith by volunteer medics.
Community Security Trust, a charity working to protect British Jews from terrorism and antisemitism, welcomed the pleas and said the four’s actions “caused immense shock and distress across the Jewish community”.
“This was an appalling antisemitic act against a volunteer ambulance service providing emergency medical assistance to people of all backgrounds across north London, simply because those ambulances belonged to a Jewish charity,” a spokesperson added.