By Andrea Thomas 

DRESDEN, Germany--U.S. Treasury Secretary Jacob Lew urged international finance officials to resolve the standoff over Greece's bailout package as quickly as possible, reflecting global jitters that a possible Greek exit from the eurozone may destabilize the world economy.

"The sooner there is a serious conversation, the better," Mr. Lew said about Greece's negotiations with its international creditors, speaking on the sidelines of a meeting of the financial chiefs from the Group of Seven leading nations. "Waiting till the day or two before, or whenever the next deadline is, is just a way of courting an accident."

He also said Greece needs to make tough decisions and that Athens has to bring forward "a credible plan."

Mr. Lew's direct language came in contrast to meeting host Germany, which sought to play down the role the Greek standoff had at the gathering. German Finance Minister Wolfgang Schäuble acknowledged Greece and its creditors, which include Germany, remained far from a deal.

"It was an issue, but we spent only a few minutes on it," Mr. Schäuble said of Greece in concluding comments Friday. "The positive news coming out of Athens doesn't fully reflect the state of talks of the Greek government with the three institutions."

The three-day gathering of finance ministers and central bank governors had other issues on the agenda: making the global economy more dynamic; assessing the risks stemming from loose monetary policy; closing remaining gaps in financial market regulation; and achieving closer international cooperation in tax matters.

But it was clear in officials' public comments and sideline conversations that the most urgent matter in global finance was the bailout talks between the Greek government and its international creditors--the European Union, the European Central Bank, and the International Monetary Fund.

Greece is under pressure to strike a deal as it is due to repay a EUR300 million ($329.2 million) loan to the IMF due June 5 and three further payments to the fund later that month totaling about EUR1.25 billion.

Concern over Greece's ability to repay its loans, and the risk of a possible, even accidental default, have rattled European stock markets and pushed the euro lower earlier this week.

International Monetary Fund head Christine Lagarde added to jitters in comments in a German newspaper interview in which she wouldn't rule out a Greek exit. International lenders on Friday insisted they weren't considering pushing Greece out of the currency.

"There is no Grexit scenario," French Finance Minister Michel Sapin told reporters, using the colloquial term for a Greek exit from the eurozone.

The meeting of the Group of Seven finance ministers--representing the U.S., U.K., Germany, France, Italy, Canada, and Japan--came just over a week before the leaders of those countries gather in southern Germany for their annual meeting, known as the G-7.

At the meeting this week, finance ministers also discussed the best ways to enable sustainable global economic growth. The U.S.'s Mr. Lew urged more investment and consumption, in a veiled dig at Germany's export-dependent economy, which U.S. officials often criticize for its heavy trade imbalance.

"There is a broad view that countries need to take comprehensive measures to boost economic growth," Mr. Lew said. "In my conversations, I emphasized the need for more demand, particularly in countries with large current account surpluses."

Andreas Kissler contributed to this article.

Write to Andrea Thomas at andrea.thomas@wsj.com