Merkel's spokesman Steffen Seibert said the visit was called off "by mutual agreement with the government of Tunisia". He declined to give a reason but the Financial Times Deutschland mentioned security worries in a preview of its Thursday edition.
The chancellor took a conciliatory tone with Germany's large Muslim community during a call-in event with her party followers late on Wednesday. With more than 3 million Muslims living in Germany, Islam had become "a part of us", she said.
"The majority of Muslims in Germany have clearly distanced themselves from such actions," Merkel said of violent protests this month against the film "The Innocence of Muslims", during which Germany's embassy in Sudan was stormed.
The German government has criticised the film as a crude attack on Islam, Foreign Minister Guido Westerwelle calling it an "anti-Islamic hate video". German authorities say they will consider banning any attempt to screen it.
