Mario Draghi said at the ECB forum in Sintra, Portugal "If the euro zone economy deteriorates in the coming months, the central bank will announce further stimulus".
"In the absence of improvement, and if kept inflation going far from our target, additional incentives will be needed," Draghi said.
Euro fell more than 0.3% against US dollar within minutes after the comments, hitting a two-week low of $1.1181.