Which is one of the ways that Great Britain interfered with American exports in the years before the War of 1812?

Great Britain blockaded the American coast to prevent U. S. ships from exporting goods to France.

At the time after the U. S. independence (1776) and the British-American War (1812), the British Empire still had a huge control over marine trading routes in the North Atlantic. That directly affected the American trades with both Britain and France, U. S. best commercial partners at the time, as they were at war (French Revolution and Napoleonic Wars, from 1792 to 1815) and blocked many of the American routes. One way for the British to negatively impact the trades between the U. S. and France was the reinforcement of the Rule of 1756, which did not allow their trades during peace times and war times, in the years of 1793 and 1794, mainly at the Caribbean Sea.