Residential transactions fell to 99,270 last month, down 0.8% from levels seen in June and 3.2% lower year-on-year, according to HMRC data.
The summer months are traditionally when sales are at their highest, meaning transactions could fall lower towards the tail-end of the year.
The number of transactions has been falling year-on-year since the start of 2018.
Critics blamed the stagnating market on the lack of supply.
Kevin Roberts, director at Legal & General Mortgage Club, said: “A fundamental imbalance between supply and demand continues to stifle movement within the market, and until this issue is properly addressed, homeowners will find it difficult to downsize or upsize into better suited properties.
“The lack of availability of appropriate housing at all stages of homeownership is restricting movement in the market and creating bottlenecks.
“It’s therefore crucial that the industry continues to take whatever steps it can to ease this block and make the UK housing market accessible for all.”
However, the July data is more positive than June, according to Jeremy Leaf, north London estate agent.
He said: “July’s HMRC data is more encouraging than the previous month’s in that the transaction levels are not declining by as much as they were.
“This reflects what we are seeing on the ground – a broadly flat market with one month up, one month down, and no clear pattern.
“Certainly we are not seeing any significant change or expecting any as the market adjusts itself to the slightly higher interest rate climate and more realism, as potential buyers return from holiday and we move into the traditionally busier autumn season.”