Embrace the Middle East was speaking after Kadiza Sultana (17, above middle) died when the bombing obliterated her house in Raqqa in May.
She left Bethnal Green with friends Shamina Begum and Amira Abase to join Islamic State last year.
It's believed that Kadiza Sultana was trying to escape Islamic State, however, before she was killed in the warzone.
An expert has warned it's exceptionally unlikely Shamima Begum and Amira Abase will be allowed to leave the caliphate.
The Bethnal Green schoolgirls were among more than 800 Britons believed to have left the UK to join IS or other militant groups in Syria and Iraq, ITV News said.
It is thought that at least 250 have since returned. Some have faced prosecution, with others allowed to re-enter society under the watch of security services.
Metropolitan Police Commissioner Sir Bernard Hogan-Howe told MPs last year the Bethnal Green trio would be unlikely to be prosecuted if they returned to Britain unless there was evidence they had committed any specific crimes while with IS.
Speaking on Premier's News Hour Jeremy Moodey, from Embrace the Middle East, said: "The bombardment of the city [of Raqqa] by Syrian and also Russian forces has got much worse.
"The image that was portrayed to these girls of an Islamic caliphate where they'd be a little closer to heaven simply hasn't lived up to the promise.
"The rule of Isis has been truly awful... One must pray for their safety in what is a pretty brutal warzone."
Listen to Premier's Alex Williams speaking to Jeremy Moodey on the News Hour:
