The USA international scored a 68th-minute consolation goal for the Sounders in front of close to 40,000 fans at CenturyLink Field following Jermain Defoe's earlier double in his debut for the Reds.
Dempsey admits it was a 'bittersweet' feeling to score in a defeat but he suggested that Seattle performed well even though they came up short.
"It's bittersweet. It feels good to have contributed in a positive way, but at the same time we're not happy with the result," he told reporters after the loss.
"I thought we did a better job in the second half moving the ball. They kind of sat back and we're trying to grind out the three points. I thought we created some good chances, we just weren't able to get the equalizing goal."
He added: "I think it's early on in the season to really gauge our team, but there are good signs that we have character and we are fighting to do something special here.
"We came up a little bit short today in not getting an equalizer, but at the same time, I thought we showed a lot of heart."
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