A study published in Nature found that dogs can tell the difference when a human makes an intentional action versus an unintentional one.
In the experiment, dogs received three conditions: intentionally withholding a reward, unintentionally withholding a reward due to being clumsy, and unintentionally withholding a reward due to being physically prevented (a clear barrier with no opening).
Dogs waited significantly longer before approaching a reward when it was withheld intentionally than a reward that was unintentionally withheld due to clumsiness or physical barrier. This shows that dogs interpret these actions differently.
Read Dogs distinguish human intentional and unintentional action.