The West German government yesterday announced a three-year, $13 billion economic stimulus program, a step "warmly welcomed" by Treasury Secretary James A. Baker III as a contribution to the international effort "to reduce global {trade} imbalances."

But sources indicated that despite his praise, Baker is still pressing the West Germans for further expansionary efforts, especially an accelerated tax reduction program that would boost domestic demand in West Germany, thus enhancing the country's ability to import more goods. He would like the West Germans to advance, at least to the beginning of 1989, a tax cut scheduled for 1990. Earlier, Baker had urged that the date be advanced to 1988, but that possibility now seems remote.

It also can safely be assumed that Baker is hoping that the West German central bank will go through with a reduction in its 3 percent discount rate today.

Uncertainty about the discount rate cut was evident in the quiet trading in currency markets yesterday. In late New York trading, the dollar was quoted at 1.6473 marks, down from 1.6570 Tuesday. The dollar dropped to 132.57 yen from 133.40.

West Germany's industrial partners -- the United States, Japan, France, Britain, Italy and Canada -- will press Bonn for additional fiscal measures if they meet in another Group of Seven session. Without accelerated economic growth in West Germany, they contend, European economic activity will tend to stagnate in 1988.

Meanwhile, sources here, in Bonn and in Tokyo agreed yesterday that no date has been set -- even privately -- for a G-7 meeting. Bank of Japan Gov. Satoshi Sumita told a press conference that a new G-7 meeting would be meaningless unless it is certain to produce a result "convincing" to currency markets.

West German Finance Minister Gerhard Stoltenberg said in Bonn that many "basic questions" need to be answered before a G-7 meeting can take place, a reference to uncertainties about legislative implementation of the U.S. deficit-reduction package.

But a senior West German official said that the new package announced yesterday, coupled with an earlier tax relief package for 1986-1990 that he estimated at about $23 billion, gives the Bonn government a solid platform at a G-7 meeting.

Baker, who has been critical for much of the past year of what he regards as West German slowness to see the need of stimulating its economy, seemed to be going as far as he could yesterday to praise what others have described as a modest effort.

The Treasury statement said: "Treasury Secretary Baker today warmly welcomed the measures announced by the Federal Republic of Germany to support additional growth in the German economy." He said the measures include "a commitment not to offset revenue losses in the 1988 budget, and steps to deregulate the Germany economy. If fully implemented, these measures should boost domestic demand in Germany, and contribute to the coordinated international effort to reduce global imbalances."

As was anticipated, the West German program contemplates a a $13 billion expansion of investment for municipalities and businesses during a three-year period.

Baker's reference to deregulation apparently was a comment on a joint statement from the Economics and Finance ministries to the effect that the government will continue to pursue its previously announced privitization policies.