Muslim leaders are writing to hundreds of mosques appealing for help in finding the London bombers.
Backlash: Mosque fire in Leeds under investigation
Warning Muslim neighbourhoods could face a backlash, the Muslim Council of Britain (MCB) said police were patrolling near places of worship.
There have been reports of attacks to mosques in London, the Midlands, Merseyside, Yorkshire and Bristol.
Church leaders have pledged to stand by Muslim colleagues, saying terrorism affects all communities.
In the letter to mosques, Sir Iqbal Sacranie, head of the MCB, said unscrupulous elements of society, including in the media, were already using the London attacks as a means to undermine the position of Muslims in British society.
"There have already been several arson attacks and criminal damage reported on mosques in various parts of the country, including Leeds, Tower Hamlets [east London], Merton [south London] Telford and Birkenhead," he said.
SUSPECTED MOSQUE ATTACKS
Bristol, two incidents
Tower Hamlets, East London
Merton, South London
Pakistani Consulate, Bradford, also attacked
"We have been in touch with the police and have been informed that the police service have put into effect patrols and consultations to reassure and protect all people of the country."
Home Secretary Charles Clarke met Sir Iqbal and other faith leaders after the blasts to devise a plan to protect Muslims or other minorities in the wake of a bomb attack. That plan involves close co-operation between Muslims and other faiths, principally churches and Jewish communities.
But Sir Iqbal said: "Regrettably, it appears that some prominent media commentators well-known for their hostility to Islam and Muslims have also decided to take part in this mischievous campaign.
"There is no need however to be daunted or intimidated by their Islamophobic propaganda. We should continue to lead our daily lives normally and in accordance with the tenets of Islam. We have raised our concerns about their provocative behaviour with the Home Secretary Charles Clarke."
Home Secretary: Met faith leaders on Friday
The MCB received approximately 30,000 hate e-mails immediately after the bombs. An analysis of the mail has led the organisation to believe it could be the work of just a small number of people who launched a "denial of service" computer program designed to crash the MCB's website.
While police say community relations are reassuringly calm, anecdotal reports from racism-monitoring organisations suggests there may have been an increase in random acts of verbal abuse of Muslims, or people who appear to be so.
Muslim organisations had reported a number of vandalism or criminal damage incidents at mosques around England.
On Monday afternoon Bristol police appealed for calm after two mosques in the city were targeted, one on Friday night and the second on Sunday.
Archbishop of Canterbury Dr Rowan Williams has already warned against the temptation to scapegoat Muslims for the attacks, widely believed to be the work of Al-Qaeda- inspired group.
The day after the bomb key faith figures from the East End of London, including Christians, Jews and Muslims, gathered near the Aldgate bomb site in a show of unity, a move then repeated on Sunday by national leaders of the three faiths.
Speaking at the Church of England General Synod in York, Dr Williams said he had heard of the blasts while visiting local Muslims in Batley, West Yorkshire.
"Routine friendship and co-operation remains the best hope we have in any conflict of finding ways forward," said Dr Williams.
"Nothing really can substitute for face-to-face encounter when even the sharpest differences of conviction, and no-one in Batley was out to deny these, can be held with respect."
Sir Iqbal said that Muslims should do all they can to counter claims that the London attacks were carried out by "Islamic terrorists", saying that such wording suggested that Islam as a faith was responsible for the bombings.
"Equally reprehensible are offensive statements by politicians of other countries seeking to demonise Muslims in Britain," said Sir Iqbal, referring to comments attributed to a number of Israeli politicians. Ariel Sharon, Israel's prime minister, is reported by agencies to have told ministers not to comment on the attacks, other than to offer sympathy. Two ministers are said to have equated the attacks with Palestinian bombings in Jerusalem.
"Let us be absolutely clear: those who planned and carried out these heartless attacks - whoever they are and whatever faith they may claim to profess - are surely the enemies of all of us, Muslims and non-Muslims," said Sir Iqbal.
"It is the duty of all of us to help bring the perpetrators of this tragedy to justice speedily. It is quite possible that if they are not caught soon, these criminals may attempt to carry out yet more atrocities in the near future. They must be stopped."