The former Chelsea star has scored three goals in two games, including the equaliser in a 1-1 Premier League draw against his old club on Sunday.
Speculation the New York City-owned Lampard could stay in Manchester beyond January 1 has followed.
But the 36-year-old refuses to think too far ahead and said the deal remained unchanged.
"It's quite simple. I'm contracted to the start of January and that's how it is at the moment," Lampard said.
"When I signed for City on loan, six weeks or so ago, it was always until January and that's the way it remains.
"I wouldn't want to get too far ahead of myself. It's not my place to do that. Obviously it would be a club decision, first and foremost, anyway."
Lampard said he was unsure what would happen with his deal and is focused on performing well when he gets his chance.
"That argument has come up since I scored at the weekend. I think the important thing for me is to train well, play well if I can, and then see what happens," he said.
"I signed on here until January, so that's all I can say at the minute. I honestly don't know. I'll train and play as well as I can and the rest is up to the club."
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