"To win the Champions League, you have to overcome a lot of things, that's what makes some sportsmen better than others," Guardiola told reporters.
"Things happen and you have to overcome then."
"We have won a lot in the last four years, but we have also drawn and lost matches.
"After a draw or defeat, we have never complained about a refereeing decision or the pitch, maybe we have done so after winning but not after a draw or defeat."
Barcelona players felt they should have had a penalty early in the match when forward Alexis Sanchez appeared to be tripped by Milan goalkeeper Christian Abbiati.
Their players also struggled to keep their footing on a San Siro pitch where huge divots were frequently thrown up.
"If UEFA want teams to put on a spectacle, they have to overcome problems like this," Guardiola said. "I don't think it's Milan or Inter Milan's problem, I think the problem is with the stadium."
Guardiola also heaped praise on his defence, often overshadowed by the exploits of Lionel Messi, Xavi and Andres Iniesta. Javier Mascherano and Carles Puyol snuffed out the threat of Zlatan Ibrahimovic and the Milan front-line.
"Mascherano and Puyol were impeccable," he said.
