"The declining trend in underlying inflation has continued, and the past interest rate increases keep being transmitted forcefully into financing conditions," the ECB said.
With Thursday's decision, the ECB left the rate it pays on bank deposits, the benchmark for borrowing costs in the euro zone, at 4.0% - its highest level since the ECB was created - and repeated it would stay there for some time.
"The Governing Council is determined to ensure that inflation returns to its 2% medium-term target in a timely manner," the ECB said. "Based on its current assessment, the Governing Council considers that the key ECB interest rates are at levels that, maintained for a sufficiently long duration, will make a substantial contribution to this goal."
Before the announcement, investors were betting on the ECB to start cutting that rate as soon as April and to continue doing so at each meeting until the end of the year to leave it at 2.50%-2.75% in December.
But most ECB policymakers have been trying to cool the market's enthusiasm, saying more data was needed, particularly about wage growth.
The ECB's two other rates were also left unchanged. Banks will be charged 4.50% to borrow at the ECB's weekly auctions and 4.75% at daily ones.
Attention will now turn to ECB President Christine Lagarde's 1345 GMT news conference.
(Reporting By Francesco Canepa; Editing by Catherine Evans)
