The Thai national team took the lead with a long-range strike by Sarach Yooyen after 23 minutes at Rajamangala Stadium in Bangkok.
However, China struck back with goals from Wu Lei and substitute Wang Shangyuan to secure a 2-1 win in Group C of Asian qualifying.
Speaking to reporters after the match, Polking said he was disappointed with his team's performance.
"We are very disappointed with the outcome of this match because our goal was to compete with China for a chance to advance to the next round.
This is not the result we expected at all. Certainly, from now on, the Thai national team cannot afford to miss out again. We need to quickly focus on the next match and forget about this game," he said.
"I can confidently say that it's not over yet. It's only the first match and I believe that we are stronger than this. We will continue to maintain the goals we have set for ourselves in the upcoming matches," he added.
However, attacking midfielder Chanathip Songkrasin was unlikely to play in the next qualifier against Singapore as he has not recovered from injury, Polking said.
He added that he still had faith in the team, stating that there were strong players among the 26-man squad who could step up and fill positions. He said he was confident the team has enough quality players to secure victory in Tuesday’s away game against Singapore.
After the opening round, South Korea leads Group C by three points following a 5-0 home victory over Singapore. China is in second place on goal difference also with 3 points from a win. Thailand and Singapore will vie against each other to win their first points on Tuesday evening.