The Community Security Trust has said that the English Defence League should be shunned after a march in east London ended when a gang of youths attacked police officers.
According to organisers Unite Against Fascism (UAF), around 5,000 people turned up for the march as a response to a planned protest by the EDL, which was later cancelled.
Protesters chanted, "EDL, Nazi scum", during the march on Sunday.
According to police, a group of 300 "volatile" men gathered outside the East London Mosque in Whitechapel Road in response to rumours that the EDL was planning to be there after all. Police officers were attacked by the crowd. A 19-year-old was arrested on suspicion of aggravated bodily harm and later released on bail.
Earlier this month the EDL launched a "Jewish Division", encouraging the community to "lead the counter-Jihad fight in England". A group on Facebook has more than 500 followers.
A spokesman for the CST said: "This shows how communal tensions increase whenever the EDL even threaten to hold a march." The UAF's Weyman Bennett said: "The EDL said they would come… they have failed."