Not quite. The constitution has a cutout for official duties of the office. The president must faithfully carry out the duties of the office. So knowingly lying can fail that test.
If you want someone to blame for the US invasion of Iraq, blame Italy, their Intelligence apparatus, and Nicolò Pollari in particular. He submitted the “Iraq is buying Yellowcake” to the CIA twice, who figured out it was a forgery before setting a private meeting with the vice president who did not know the CIA had already ruled it out.