Moyes' men go into Tuesday's Champions League  visit of Shakhtar Donetsk on the back of consecutive home Premier League defeats against Everton and Newcastle United.
United are yet to taste defeat in the Champions League this season and have already qualified for the last 16, but sit ninth in the Premier League, some 13 points adrift of leaders Arsenal.
Former Everton boss Moyes refused to shirk the blame for those setbacks, and is eager to get the English champions back on track.
"[Losing to Newcastle] raised my spirits," Moyes said. "[The result] made me more determined.
"I take complete responsibility for the results. They've been good in the Champions League but not so good in the Premier League. I would like them to be much better, and I've got no doubt they will.
"It is tough because we expect to win all the games. We have been inconsistent at times and we have played very well in some of the games in the Champions League, not so well in the Premier League, albeit we have lacked a little bit of good fortune at times.
"I think there is a bit of everything that could with better, we'd like to pass it better, we'd like to create more chances, we'd like to defend better when those situations arise, it's all round we'd like to improve. It's only a few weeks ago we were talking very well about the team."
The three-time Champions League winners can top Group A if they avoid defeat against the Ukrainian champions, a scenario that would likely hand them a less difficult tie in the first knockout round.
"It's important to give ourselves the best possible chance we have in the next round," Moyes added.
"But the big job was to make sure we qualify for the group, that part is done, but hopefully we can finish the group unbeaten. And if we do that then that will see us through."