According to The Mirror, Moffat explained that he was worried fans wouldn't enjoy the new series.
"I have never done a job that has had so much pressure," he said. "It is extraordinary pressure."
However, Moffat added that he feels much better now because of the positive reaction to the show's new stars Matt Smith and Karen Gillan.
"The pressure lifted in another sense quite recently," he said. "When Matt Smith's first episode went out and Matt and Karen became the toast of the nation, I thought, 'Well, that's a relief'. Because up until that point I was thinking, 'Well, I could be a novelist at the end of the year'."
Doctor Who concludes on Saturday at 6.05pm on BBC One.