The federal government moved yesterday to ban the sale of certain types of toys that have parts small enough to be swallowed by children three years and under, and cause choking or suffocation.

Citing a special three-month study completed earlier this year, the Consumer Product Safety Commission said 25 children, under the four years of age died from small parts ingested during that period.

The proposed ban, which is subject to 60 days of public comment before it can become final, would apply to such toys as block, jack-in-the-boxes, stuffed toys, teethers and some squeeze toys.

The commission said about 90 percent of the domestically manufactured toys that would be affected by the ban already meet the requirements, but a large number of imported toys could be banned if not changed.

The ban will not be in place in time to change toys sold during this Christmas season, and depending on when the commission makes the action final, it may not even affect next year's Christmas sales.

Some toys are exempted from the proposed regulations. This group includes children's clothing, finger paints, modeling clay, marbles, balloons and crayons.

Although small toys in vending machines will be covered, the commission voted against banning the machines themselves.

The commission vote for the ban was unanimous, although commissioner Edith Barksdale Sloan said she would have preferred the ban to include items sold for children aged five and under.

The test to see what toys would be banned employs a cylinder measuring 1.25 inches in diameter and 2.25 inches in depth. If any toy can fit entirely into that cylinder, or if a part of a toy can come off and fit in that cylinder, the toy would be banned.

In the calendar year 1976, CPSC said, children's products, exluding crayons and marbles, were responsible for 3.829 injuries that required hospital emergency room treatment.

Products intended for use by children less than three years of age are estimated to account for 2,614 of these cases.