"Questions like the attack on Afghanistan, the expansion of instability and insecurity in the region and America's backing for terrorism were raised in the letter," said Esfandiar Rahim Mashaie, the Iranian presidency's chief of staff.
"The president has also asked Obama to learn from Iran how to combat terrorism," Mashaie said.
In his letter written in the Iranian month of Esfand (Feb 20 to Mar 21), Ahmadinejad raised the issue of Sunni militant Abdolmalek Rigi, who was arrested by Iran in Feb and charged of being supported by America.
"The aim of writing this letter is for the world to grasp the view of the Islamic republic of Iran and also criticise US policies in the region," Mashaie said.
A similar letter was sent to Obama's predecessor George W Bush in May 2006, followed by an open letter to the people of America.
In line with his doubt expressed over the 9/11 attacks on United States, Ahmadinejad has also written to the UN Secretary General Ban Ki-moon to investigate 2001 attacks, which he claimed was a 'big lie'.