Malala said that she and millions of others throughout the world mourn the lives of the children who died in the Taliban assault on a school in Peshawar.
"Innocent children in their school have no place in horror such as this," said Malala, 17. "I condemn these atrocious and cowardly acts."
Malala is herself the survivor of a Taliban attempt to silence her. In a bid to stop her work lobbying for girls' right to education, a Taliban gunman shot her in the head at close range in Pakistan two years ago.
She survived and now lives in Birmingham, England, where she is continuing to fight for equal education.
Malala, who has expressed an interest in going into politics in Pakistan once her education is completed, said she stands "united" with the government and armed forces of Pakistan in their response to the attack.
She received the Nobel Peace Prize at a gala ceremony in Norway last week.