Speaking to a French magazine on Tuesday, Butrus Butrus-Ghali said Jose Zapatero was simply acknowledging the 90% majority of Spanish citizens who did not want their country to go to war.
However, the former UN chief added that a Spanish "withdrawal will only have symbolic value and will not make a big difference to coalition forces" in Iraq.
Butrus-Ghali's commments come after Zapatero's interview on a Spanish radio station on Monday in which he said: "Spanish troops in Iraq will come home."
"The war in Iraq was a disaster, the occupation of Iraq is a disaster."
Spain sent 1300 troops after a US-led invasion force ousted Saddam Hussein in April last year.
Commentators in Spain and abroad saw the election defeat for Aznar's right-wing government as a punishment for its unpopular decision to back the US-led war on Iraq and commit forces to that country's occupation.
"The war in Iraq was a disaster, the occupation of Iraq is a disaster"
Spanish prime minister elect
Millions took to the streets during war protests in February last year to oppose Aznar's decision to contribute troops.
The bomb attacks in Madrid on Thursday that killed 200 people and injured 1500 more, just three days before elections, are also believed to have brought home the implications for involvement in the US-led war.
The train attacks that have been attributed to an al-Qaida threat to strike against US allies in the Iraq occupation helped tip the scales against the Popular Party and in favour of Zapatero's Socialist Party.
Butrus-Ghali, also a former Egyptian foreign minister, concluded that Islamist violence "could get worse if no solution is found to the number one problem [in the Middle East] - Palestine".