International competition has prompted President Reagan to remove restrictions on civilian U.S. satellites, allowing them to make and sell much more finely detailed photographs of the planet, White House officials said yesterday.

Until now, the government prohibited private companies from lofting satellites that could photograph clearly, or "resolve," objects smaller than 10 meters, or about 32 1/2 feet, in size. The Defense Department had sought the constraints in an effort to protect military secrets.

Recently, however, the Soviet Union began marketing highly detailed satellite photos, down to a resolution of five meters, of any part of the world outside its own territories. Scientists at the U.S. Geological Survey have petitioned the government to let them buy the Soviet product, including photographs of the District of Columbia.

U.S. military satellites can make classified images of objects measured in inches, experts said, but the civilian U.S. Landsat satellite, which once had a global monopoly, can detail objects no smaller than 30 meters, or about 97 1/2 feet. The government has allowed Landsat to wither, surrendering business to foreign rivals, including the Soviet Union and France, in part because the market for satellite photos has been slower to develop than expected, according to some experts.

However, other experts foresee increasing use of such photos by journalists, scientists and others.

The new approach to satellite imagery was contained in an expanded space policy approved by Reagan earlier this month, and which will be included in the legislative package to be sent to Congress Monday, officials said. The policy is part of a push to "foster a purely commercial, market-driven space industry without direct government subsidies."

Some restrictions remain. For example, regulations issued recently by the Commerce Department give the State and Defense departments a veto over public acquisition of satellite photos if they pose a national security threat.