But in his introductory statement to a press conference, ECB President Mario Draghi said it was too early to judge whether the recent fluctuations in financial markets and renewed downside risks would affect the outlook for inflation or whether it was merely a transitory phenomenon.
The outlook for the economic recovery in the euro zone and a return to higher inflation was "somewhat weaker" than the ECB had expected, Draghi said, adding that the current asset purchase programme was flexible enough so it could be adjusted in size, composition and duration.
The ECB embarked on its asset purchase programme - known as quantitative easing - in March, buying 60 billion euros of mainly bonds issued by its member states each month.
The programme, which so far has resulted in falling bank lending rates, is planned to run until the end of September 2016, or beyond if necessary, until the ECB is confident that inflation is headed toward its target of below, but close to 2.00 percent.
Inflation in the euro zone has been unchanged at 0.2 percent in June through August, reflecting the fall in energy prices, but is forecast to slowly rise toward the end of the year and then pick up further in 2016 and 2017 as the economic recovery gathers strength and the pass-through of a lower exchange rate of the euro dissipates.
"However, this increase in annual inflation rates is currently expected to materialize somewhat more slowly than anticipated thus far," Draghi said.
ECB staff lowered its 2015 inflation forecast by 0.2 percentage points to 0.1 percent and the 2016 forecast to 1.1 percent from 1.5 percent forecast in June. For 2017 the ECB expects inflation to average 1.7 percent, down from a previous forecast of 1.8 percent.
While Draghi expects the euro zone's economic recovery to continue, the pace will be lower than previously expected due to the slowdown in emerging markets that cuts into euro zone exports.
"The risks to the euro area growth outlook remain on the downside, reflecting in particular the heightened uncertainties related to the external environment," Draghi said.
The euro zone's Gross Domestic Product expanded by 0.3 percent in the second quarter of this year from the first quarter's 0.4 percent for annual growth of 1.2 percent, up from 1.0 percent.
For this year, the ECB trimmed its growth outlook to 1.4 percent from a previous expectation of 1.5 percent and for 2016 it cut the forecast to 1.7 percent from 1.9 percent. For 2017 the ECB expects growth of 1.8 percent, down from 2.0 percent forecast in June.
The European Central Bank issued the following statement by its president, Mario Draghi: