Industrial goods accounted for much of the fall in exports.
The figures come amid growing concerns about the US economic recovery and the country's high debt levels.
Total exports for the month fell by $4.1bn to $170.9bn, while imports fell by $1.9bn to $223.9bn.
Consumer goods exports actually increased, while cars and car parts were virtually unchanged from the previous month.
Imports and exports of services were virtually unchanged.
The US's deficit with China grew to $26.7bn, up from $25bn in May, while that with the European Union rose by $1bn to $9.8bn.
The US recorded a trade surplus with Hong Kong, Australia, Singapore and Egypt.
Source: BBC News