Workspace saw a year-on-year fall in average monthly customer enquiries in the third quarter from 1,009 to 858.
Enquiries in October and November averaged 1,015 per month, but the seasonal downturn in December was more marked this year.
Lettings in the quarter averaged 86 per month compared to 85 per month in the same quarter last year.
The company said it has seen good levels of customer demand in January 2018, with 489 enquiries in the first two weeks.
Occupancy at The Record Hall in Holborn, which opened in May 2017, reached 73% by the end of December 2017.
Over 483,000 sq ft of new and refurbished space is due to complete in 2018.
Net debt reduced by £26m in the quarter to £396m at 31 December 2017, with cash balances and undrawn facilities of £269m.
Jamie Hopkins, chief executive officer of Workspace Group, said: "With our marketing expertise, coupled with ownership of the right real estate, I believe Workspace is well positioned to take advantage of the growing interest from all kinds of businesses in our inspiring, well-connected spaces."