The Muslim leaders say youngsters are being brainwashed and manipulated into fighting for agendas they barely understand.
Last week, some 100 imams from both Shia and Sunni communities across the United Kingdom made an appeal in an open letter, calling on British Muslims to refrain from traveling to Syria and Iraq  to fight in those countries.
The religious leaders called for unity among Muslims, telling Britons that if they wished to help, they should focus on sending humanitarian aid and charity to the innocent people caught in the fighting.
One of the signatories, Masood Hazarvi, a professor and imam based in Luton, north of London, said that although there is a jihad concept in Islam, the fighting in Syria and Iraq is not a jihad as it does not follow the terms or conditions for such a move.
The development comes amid concerns by British as well as European officials over the growing national security threat posed  by the European militants returning from Syria. Fears are growing that the European militants coming with experience from Syria may carry out terrorist attacks in their home countries.
An estimated 500 Britons  have traveled to Syria to fight along the extremist militants there.
Syria has been gripped by deadly violence for more than three years. According to some sources, over 160,000 people have been killed  and millions of others displaced due to the violence.
In addition, some British militants are also believed to have crossed into Iraq, where violence escalated last month, with the ISIL terrorists taking control of large swathes of the Arab country.