Condoleezza Rice, the US secretary of state, said in Washington that "Iran and Syria have gone out of their way to inflame sentiments" that have produced violent protests across the Muslim world against publication of the caricatures.
"That is 100 per cent a lie," Isfandiar Rahim Mashaee, one of several Iranian vice presidents, said during a visit to Indonesia. "It is without attribution."
The demonstrations - directed mostly at the foreign missions of Denmark, where the cartoons were first published - turned deadly this week in Afghanistan, where nine people have been fatally shot in clashes between demonstrators and security forces.
The images - including one depicting the prophet wearing a turban shaped as a bomb - have been reprinted in mostly Western media. Islam is interpreted to forbid any illustrations of Prophet Muhammad.
In Muslim-majority Malaysia, a newspaper that published one of the caricatures said it expected its printing licence to be suspended by the government, while police launched an investigation over the issue.
"We may not have publication of the newspaper by tomorrow"
Sarawak Press executive director
The Sarawak Press newspaper group has faced relentless public criticism despite apologising for what it says was an editorial oversight that led to the publication of the caricature in its Sarawak Tribune last Saturday.
Polit Hamzah, the Sarawak Press executive director, on Thursday said: "We may not have publication of the newspaper by tomorrow."
Police questioned the editor who authorised the cartoon's publication for two hours on Thursday and were examining whether the paper's management broke any laws, the national news agency, Bernama, cited Sarawak's police chief Talib Jamal as saying.
The editor, Lester Melanyi, resigned over the controversy.