The annual rate of house price inflation fell to 7.2% in February - down from 8.4% in January, and the lowest rate for more than a year.
However, in the short term, between January and February, prices rose by 0.6% on a seasonally-adjusted basis.
The average house price across the UK is now £268,000, the ONS reported.
Separate figures show that mortgage lending fell significantly in February, according to the Council for Mortgage Lenders (CML).
The number of loans advanced to borrowers during the month was 40,600 - a 1% fall from January, and a 16% fall compared with February 2014.
Paul Smee, the CML's director general, said seasonal factors had not helped the market.
"This typical seasonal trend may also be exacerbated by uncertainty ahead of the general election, but we still expect to see an upturn in the spring and summer months," he said.
House prices across the UK are continuing to cool down, according to figures from the Office for National Statistics (ONS).