Criticism is mounting from religious and political leaders in the Muslim world following remarks by Pope Benedict XVI about Islam.
There have been street protests in several countries
Pakistan's president, Pervez Musharraf, spoke of "sinister tendencies to associate terror with Islam" which gave rise to an "alienation with the West".
Pope Benedict, who is back in Italy, is said to be upset at the way in which his remarks have been interpreted.
Correspondents say his visit to mainly Muslim Turkey in November is in doubt.
Speaking in Germany on Tuesday, the Pope quoted a 14th Century Christian emperor who said the Prophet Muhammad had brought the world only "evil and inhuman" things.
'Take full responsibility'
One Anglican church and one Orthodox church were reportedly firebombed in the West Bank city of Nablus.
A group which said it carried out the attacks, calling itself the Lions of Monotheism, said they were protesting against the Pope's remarks.
Speaking at the Non-Aligned Movement's summit in Cuba, Gen Musharraf added his voice to those of a host of Muslim leaders who have criticised the Pope.
"Our strategy must clearly oppose the sinister tendencies to associate terrorism with Islam and discrimination against Muslims, which are giving rise to an ominous alienation between the west and the world of Islam," he said.
At the same meeting, Malaysian Prime Minister Abdullah Ahmad Badawi said the Pope had to do more to calm Muslim emotions.
"The Pope must not take lightly the spread of outrage that has been created," he said, quoted by Malaysia's Bernama news agency.
"The Vatican must now take full responsibility over the matter and carry out the necessary steps to rectify the mistake."
But German Chancellor Angela Merkel defended the pontiff, saying critics misunderstood the aim of the speech.
Meanwhile In Turkey, the first Muslim country the Pope is due to visit in November, the BBC's Sarah Rainsford says the criticism is mounting, not fading.
So far, there have only been minor street protests, she says, but there is widespread anger at the Pope from Turks, many of whom are still smarting at the Pope's previous comments - that Turkey belongs to a different cultural sphere and has no place in Europe.
The BBC's Arab affairs analyst, Magdi Abdelhadi, says the reason for the vehemence of Muslim reaction is simple: America's global "war on terror" is perceived by many Muslims as a modern crusade against Islam.
But he says the culture of 24-hour news, whereby comments can be taken out of context, disseminated and recycled, has also played a part.
'Renunciation of violence'
In Germany, the Pope's homeland, Chancellor Merkel said the Pope had spoken in favour of dialogue between religions, "which is something I also support and consider urgent and necessary.
"What Benedict XVI emphasised was a decisive and uncompromising renunciation of all forms of violence in the name of religion," she said.
The Vatican has also rejected the interpretation of the pontiff's remarks as an attack on Islam, and has said he intended no offence.
In his speech at Regensburg University, the German-born Pope explored the historical and philosophical differences between Islam and Christianity, and the relationship between violence and faith.
Stressing that they were not his own words, he quoted Emperor Manuel II Paleologos of the Byzantine Empire, the Orthodox Christian empire which had its capital in what is now the Turkish city of Istanbul.
The emperor's words were, he said: "Show me just what Muhammad brought that was new and there you will find things only evil and inhuman, such as his command to spread by the sword the faith he preached."
Benedict said "I quote" twice to stress the words were not his and added that violence was "incompatible with the nature of God and the nature of the soul".