FRANKFURT — The president of the European Central Bank issued a sober assessment of the euro zone economy, saying on Thursday that he was “very, very cautious” about prospects for growth and acknowledging concern about shock waves from the civil war in Syria.

“I can’t share the enthusiasm” about budding growth in the euro zone, Mario Draghi, the bank president, said at his monthly news conference. “These shoots are still very, very green.”

The central bank kept its benchmark interest rate at a record low of 0.5 percent on Thursday, which had been expected after recent economic indicators showed the euro zone economy was beginning to recover, albeit weakly. But Mr. Draghi said the bank had not ruled out future rate cuts.

“We certainly are alert to the geopolitical risks that may come from the Syrian situation,” he added.