Non-defense capital goods orders excluding aircraft, a closely watched proxy for business spending plans, fell 3.3 percent, breaking four straight months of gains. It was the biggest fall since February.
Orders for these so-called core capital goods increased by a revised 1.3 percent in June.
Economists had expected this category to increase 0.5 percent after a previously reported 0.9 percent gain in June.
The decline in orders for both durable and capital goods suggested manufacturing will probably not bounce back as quickly as many economists had expected after hitting a speed bump early in the year.
That, combined with a slowdown in residential construction and new home sales, implies the economy might not accelerate much from the second quarter's 1.7 percent annual pace.
Last month, durable goods orders were held down by a 19.4 percent plunge in bookings for transportation equipment. That reflected a 52.3 percent drop in orders for civilian aircraft.
Boeing received orders for 90 aircraft in July, down from 287 aircraft the prior month, according to information posted on its website. Orders for motor vehicles gained 0.5 percent after rising 0.2 percent the prior month.
Even excluding transportation, demand for long-lasting manufactured goods was weak almost across the board. Orders excluding transportation fell 0.6 percent.
There were declines in orders for computers and electronic products, and electrical equipment, appliances and components fell. Orders for machinery and primary metals were flat. Orders for defense capital goods plummeted 21.7 percent in July after hefty gains in the prior months.