It's not that they didn't try. France was attacked by Prussia and the Holy Roman Empire (Austria) in 1792. They wanted to ensure king Louis XVI would stay on the throne. In 1793 England, the Dutch Republic, Spain, Portugal, and Sweden joined the anti-French coalition. France at that point was under attack from all sides.

They just failed to win. The most important factor in France's success was the mass conscription of soldiers, creating the first true national army (other nations still relied for a large part on mercenaries and/or militias). It was during these wars that Napoleon rose through the ranks; he eventually managed to become the leader of France, ending the Revolution.