Administration sources indicated yesterday that the White House reached what was described as a preliminary commitment to attempt talks with Moscow by the end of this year on limiting intermediate-range missiles based in Europe.

The tentative decision to get these discussions under way by a cetain time was reportedly made at a meeting of the top-level National Security Council Thursday with President Reagan in attendance.

Officials emphasized that many details remain to be worked out and that there remain some differences between the State Department and the Pentagon on the approach to these talks. American allies in the North Atlantic Treaty Alliance (NATO) have been pressing the Reagan administration to set some kind of a schedule for beginning these talks, which allied leaders see as essential not only for arms control purposes but also because of the political need in Western Europe to be seen as pursuing both parts of a December 1979 NATO agreement.

The NATO ministers agreed to accept deployment of 572 U.S.-built Pershing II and cruise missiles in West Germany, Italy and England, and possibly in Belgium and Holland. Those missiles are to be a counterweight to hundreds of Soviet SS20 intermediate-range missiles already in place.

But the NATO agreement also contains a second provision that the West seek negotiations with Moscow in an effort to limit deployment of such weapons by both sides.

Those negotiations would deal only with the weapons based in Europe. They do not deal with the ocean-spanning strategic missiles and bombers based in the United States and Soviet Union and aimed at each other.

Those long-range weapons have been dealt with in the strategic arms limitation talks (SALT) between the two superpowers. While there is now some reason to believe the European talks about so-called Theater Nuclear Forces (TNF) will go ahead, there remains no sign that the long-stalled SALT talks will be resumed.

The West German government, in particular, has been anxious for a sign from Washington that the TNF talks will begin, and the Reagan administration appears anxious not to put West German Chancellor Helmut Schmidt in political jeopardy with left-wing forces in his own party by not showing some move toward these negotiations.

Secretary of State Alexander M. Haig Jr. is expected to discuss the administration's plans with the NATO allies at a minister's meeting opening in Rome tomorrow.

Among the internal questions to be worked out in Washington, sources say, was how to move ahead within the alliance, while preserving the harder line on arms control with Moscow that the Reagan administration has taken in contrast to the previous Carter administration.

The two-pronged NATO decision on European arms and negotiations was made just three weeks before the Soviet invasion of Afghanistan, and that invasion helped scuttle any progress on either SALT or TNF talks for the last 16 months.