General Motors Co.’s first-quarter North American profit disappointed investors as increased spending on sales incentives, marketing and engineering costs reduced the benefit of soaring revenue.

Excluding some items, profit was 95 cents a share, beating the 91-cent average estimate of 13 analysts surveyed by Bloomberg. Net income more than tripled to $3.37 billion, or $1.77 a share, from $1.07 billion, or 55 cents, a year earlier, Detroit-based GM said today in a statement.

While North American sales in the quarter rose $2.82 billion, higher operating expenses cut the company’s profit by $700 million, GM said today. The rising costs denied investors the results they expected and contributed to the stock’s biggest decline in more than two months, Adam Jonas, an analyst with Morgan Stanley, said in a telephone interview.

“The market thought that they would beat the consensus by more than 5 percent,” said Jonas, who’s based in New York. “Nobody owns GM to meet numbers. They own GM to beat numbers by a significant amount.”

GM fell $1.02, or 3.1 percent, to $32.02 at 4 p.m. in New York Stock Exchange composite trading, the biggest decline since Feb. 24. The shares have slid 13 percent this year.

The quarterly profit was GM’s fifth straight and its largest net income since at least 1990. GM’s total first-quarter revenue rose 15 percent to $36.2 billion.

Engineering and marketing costs each rose $200 million, and incentive spending cut profit by $300 million, GM said.

Chief Executive Officer Dan Akerson said on a call with analysts that the first-quarter results were “on plan” and the company must focus on reducing costs.

“We have a lot of work to do to leverage our scale and get the most out of our brands,” Akerson said. “A key part of improving our leverage is controlling costs.”

GM’s U.S. sales climbed 25 percent to 592,545 light vehicles in the first quarter, outpacing the industry’s 20 percent gain, according to Autodata Corp., a researcher based in Woodcliff Lake, New Jersey. The company spent an average of $3,566 per vehicle on sales incentives in the period, the most among the eight largest automakers by U.S. sales, Autodata said.

GM said it earned $2.9 billion before interest and taxes in North America in the period.

Earnings on that basis in GM’s international operations, which include China, fell to $480 million in the first quarter from $908 million a year earlier. Sales for the unit rose 8.2 percent to about 855,000 vehicles in the quarter, GM said.

The pretax loss in GM’s European operations narrowed to $390 million from $477 million. GM has said it plans to break even in Europe by the end of 2011.

Chief Financial Officer Dan Ammann said GM’s European operations are showing progress and that the region would have broken even if not for a $395 million charge to goodwill.

GM also took a charge of $106 million in its international operations related to its joint venture in India.

The automaker reported a gain of $1.6 billion from the sale of its stake in former parts unit Delphi Automotive LLP. GM posted a gain of $339 million from the sale of preferred stock in Ally Financial Inc., formerly the automaker’s GMAC Inc. unit. In total, special items boosted GM’s net income by $1.47 billion in the first quarter.

The U.S. Treasury Department, which owns 33 percent of GM, plans to evaluate the earnings before deciding whether to sell more of its investment, a person familiar with the matter said last month. The department wants to sell its stake for at least the IPO price and would prefer to sell in the high-$30 range, a person familiar with the matter has said.

The U.S. took a 61 percent ownership of GM as part of the automaker’s $50 billion government-led bailout and bankruptcy reorganization in 2009. The Treasury sold shares equal to a 28 percent stake during the November IPO of the company. The department can sell more shares starting May 22.

GM may retake the crown for most global auto sales from Toyota Motor Corp. this year, said Jeff Schuster, executive director of forecasting for J.D. Power & Associates, a research firm in Westlake Village, California. Toyota has lost production because of plant shutdowns following the March 11 earthquake in Japan. GM also is better positioned to expand sales in China, he said.

GM increased first-quarter North American truck production 18 percent from a year earlier to about 502,000 units, while car output rose 16 percent to about 284,000 vehicles.