The South Korea international midfielder accepts United will have a tough job at Old Trafford next Wednesday.
However, Park is also optimistic that his team can make it through to face the winners of Lyon and Bordeaux.
"We are disappointed because we were leading," said Park.
"The early goal was good for us but we weren't able to build on it and get the result. But we have our chance to go through at Old Trafford.
"Bayern have an experienced team, and the club has a proud history.
"They did well but the situation will be different at Old Trafford. We're waiting for them to come there."