March 27 (Reuters) - Wall Street's main indexes opened lower on Friday as the month-long Middle East conflict dragged on, weighing on sentiment despite the United States pushing back another deadline to strike Iran's energy infrastructure.

The Dow Jones Industrial Average fell 55.9 points, or 0.12%, at the open to 45,904.25. The S&P 500 fell 23.3 points, or 0.36%, at the open to 6,453.89​, while the Nasdaq Composite dropped 120.9 points, or 0.56%, to 21,287.187 at the opening bell.