The South Korean was on the mark for the Reds on Saturday, but now they are out of three competitions at early stages for United.
And United have an early chance to bounce back when they take on Stoke City at Old Trafford on Tuesday, fans will be looking for a backlash.
Speaking to MUTV Park said: "We must quickly forget about this game, move on and look to the future. We still have the Premier League and the Europa League to focus on."
Park said United arguably deserved better from Saturday's loss at Anfield, admitting a late lapse of concentration cost them for Dirk Kuyt's winner.
"We controlled the ball which is what we wanted before the game. We did that well but that couldn’t get the win for us,"Park added.
"In the team meeting, we talked about trying to keep possession and then make chances. We did that and that’s why we played very well."
"But then we lost concentration for a moment and ended up giving them the goal to make it 2-1. Everyone was quiet afterwards because we all feel disappointed."