The House Armed Services Committee yesterday took a step toward production of new chemical weapons and cut production money for the controversial Divad antiaircraft battlefield weapon by almost 50 percent, according to congressional sources.

The committee, working on the military's fiscal 1986 spending plan, also voted against allowing the Pentagon to decide where to make $1.2 billion in reductions in the president's $3.7 billion request for his Strategic Defense Initiative research program, also known as "Star Wars."

The panel made more than half the SDI reductions in two parts of the program -- the surveillance and tracking portion, which was cut $496 million, and the kinetic energy weapons portion, reduced by $350 million.

With only the military construction portion of the bill remaining, the committee was near its goal of holding next year's defense spending bill near $303 billion, $19 billion below President Reagan's request.

The panel also approved production of 21 additional MX missiles, after defeating by voice vote a move by Rep. Charles E. Bennett (D-Fla.) to reduce that number to zero. Reagan had requested 48 more MX missiles.

An amendment to limit deployments to 40 missiles was defeated, 32 to 13. "That move will do better on the House floor," one committee member said.

In other action, Chairman Les Aspin (D-Wis.) got committee approval for a $4 billion cut in the military retirement fund in fiscal 1986. The cut would not apply to the 2.1 million people now in uniform or the 1.1 million current retirees.

On the chemical weapons issue, Aspin reportedly told some committee members that he expected the funding for new weapons would be deleted on the House floor. The administration has tried to get congressional approval for new chemical weapons for three years. The United States has not produced such weapons since 1969.

The Divad amendment reduced the administration's $417 million request by $196 million and said none of the money could be made available until the defense secretary certified that the weapon had fulfilled its performance specifications, and its builder had signed a warranty to that effect.