Fethullah Gulen called Ambassador Karlov's killing a "heinous act of terror".
Around 18 Russian experts will assist the investigation into Ambassador Karlov's shooting.
The actor and gender-equality campaigner spoke to activists at the One Young World conference in Canada.
Ukraine's foreign minister said the sole communication takes place in Normandy meetings.
President Erdogan was banned from transmitting a live link to a protest in Germany.
The parody, inspired by a 1984 hit by German pop star Nena, was broadcast on national television.
The political fallout from the refugee crisis is growing.
"Do not provoke the Russian bear," said Russia's ambassador to Denmark after joking about Sweden's paranoia