The Sweden international left Camp Nou in 2010, just one year into his stint, after failing to justify the £54 million plus deal that took him away from Inter in exchange for Samuel Eto'o.
In his autobiography Ibrahimovic slammed Guardiola, claiming the 40-year-old coach was terrified of the threat posed by his Real Madrid counterpart, Jose Mourinho.
"I have no problem with Mister Ibrahimovic, but I think one always has to act naturally," Guardiola told reporters at a press conference.
"If we run into each other, I will greet him, just like the sportsmen we are."
Barca are already through to the Champions League knock-out stages, but they are still looking for a victory at San Siro in order to retain the top place in Group H.
"It is always better to be first in the group than runners-up, because it is better to play the second leg at home," Guardiola noted.
"However, to be at this stadium is a big honour and a privilege, you breathe history here.
"We must show that Spain is a country as important as Italy in terms of football against a club as important as Milan."
Guardiola then commented on the health state of assistant Tito Vilanova, who underwent surgery to remove a tumour found on his parotid gland.
"Tito is an amazing person and we hope that he will resume his everyday life as soon as possible," he added.
"The news about his tumour had a similar impact to the one about Abidal's problem, even though they are different problems."
Starting last Friday and continuing every Friday through to January, Goal.com will publish extracts from Graham Hunter's highly-anticipated book, Barca: The Making of the Greatest Team in the World, which kicked off with a fascinating segment on Lionel Messi's rise to the top at Camp Nou. Don't miss it!