Financial director Anthony di Iorio told an analyst conference call the financial crisis had made it impossible to provide an accurate forecast for the full year.
"These are very uncertain times, the markets are unpredictable," he replied when pressed to confirm the bank's outlook for pretax profit of €8.4 billion ($13.1 million).
Di Iorio added that due to the current market turmoil, Deutsche Bank could not give a forecast for its full-year results.
The bank posted a first quarter net loss excluding minority holdings of €131 million ($205 million), compared with a profit of €2.12 billion in the same period a year earlier.
Its pretax result fell to a loss of €254 million from a profit of €3.16 billion.
Deutsche Bank took write-downs of €2.7 billion after initially appearing to have escaped the worst of a financial crisis that followed the collapse of the US market for high risk, or subprime, mortgages in mid-2007.
Chairman Josef Ackermann said in a statement as saying that "in the first quarter of this year, financial market conditions were the most difficult in recent memory.
"In the month of March, pressure on the banking sector was more intense than at any time since the current credit downturn began. Inevitably, this left its mark on Deutsche Bank's results."
The bank said it had managed to offset the losses in part with €854 million in gains from the sale of shares in the German auto manufacturer Daimler, insurer
Allianz and industrial gas group Linde.
Without these gains, the net loss would have climbed to €1.1 billion.
Deutsche Bank had already warned it would be hard to hit its 2008 profit target owing to turmoil that has shaken the banking sector.
On April 1, Deutsche Bank said its lucrative investment banking unit had taken a serious hit from the US subprime turbulence, which has threatened several German banks with bankruptcy.
First-quarter results were undercut by €1.77 billion in mark-downs on leveraged loans and loan commitments, plus €885 million for commercial real estate loans and residential mortgage-backed securities.
In all, the charges came to €2.7 billion, higher than the April 1 forecast of about €2.5 billion.
Di Iorio also said the bank had sold around €1 billion worth of loans provided to finance leveraged buy-outs since the end of the first quarter.
International media had reported recently that Deutsche Bank was preparing to sell up to $20 billion worth of such loans.
Meanwhile, Ackermann stressed that the bank was "well positioned to emerge stronger than ever from the crisis.
"We are equally determined to meet near-term challenges and to take advantage of longer-term opportunities," he added.
A breakdown of the results showed that the Corporate and Investment Bank unit, normally a strong contributor, saw revenues plunge 77 percent to €1.5 billion.
Earnings from retail banking operations were stable at €2.5 billion.
Shares in the bank shed 0.47 percent to €76.41 in midday Frankfurt trade while the Dax index of leading shares was down 0.57 percent overall.
Analysts said the results were better than the market had expected, but a local trader nonetheless commented that they still looked "pretty bad" and predicted they would put pressure on the bank's shares all day.