Some 300 Muslim scholars have begun meeting in Bahrain to discuss the row over cartoons of the Prophet Muhammad.
Sheikh al-Qaradawi said a war was being waged against Islam
The conference follows a wave of demonstrations in which at least 50 people died in the wake of the images' publication in Denmark and elsewhere.
The scholars are hoping to come up with a strategy to mobilise Muslims in defence of the Prophet.
One leading hardline cleric, Sheikh Yusuf al-Qaradawi, told delegates that a war was being waged against Islam.
The cartoon controversy has strained relations between Islam and the West.
It has triggered demonstrations in many countries, boycotts of Danish goods and the resignation of government ministers in Italy and Sweden.
The row has lost some of its heat but is not yet over.
Call to Muslims
BBC Islamic affairs analyst Roger Hardy says the conference is designed to show that the sense of injury in the Muslim world is still palpable.
Egyptian-born Sheikh Qaradawi, who has a popular weekly programme on the Arab satellite station al-Jazeera, urged Muslims to rise to the defence of their Prophet.
The cartoons provoked outrage across the Muslim world
Sheikh Qaradawi and another of the conference organisers, the Saudi cleric Salman Al-Awdah, strongly support a Muslim boycott of Danish goods.
It was a Danish newspaper that first published cartoons satirising the Prophet last year.
One of the images depicted Muhammad with a turban shaped like a bomb.
The cartoons were later republished in other European newspapers.
The organisers of the Bahrain conference insist the actions they are proposing are peaceful.
The conference, in the capital, Manama, began on Wednesday and was expected to finish on Thursday.