In its latest effort to deal with the fallout from the subprime-credit crisis, Freddie Mac said it won’t purchase subprime mortgages secured by properties in New York state with note dates on or after Sept. 1.

The move is Freddie Mac’s response to recent New York legislation, effective Sept. 1, that creates a new category of subprime mortgages. The state has said the legislation is intended to curb abusive lending practices.

Freddie, a government-sponsored mortgage buyer, said the pending law “creates the potential for heightened legal and business risk exposures for the purchasers or assignees of these loans,” including secondary-market participants, such as Freddie and sister Fannie Mae, that buy mortgages.

Freddie last week said it planned to slow growth in its portfolio of mortgage-related securities after reporting a second-quarter loss on $2.5 billion in credit-loss provisions and $1 billion in securities write-downs.

In scaling back purchases of home mortgages, Freddie Mac — the second-largest buyer of mortgages in the U.S., following Fannie — will likely bring about higher borrowing costs for homeowners. It may also hobble the already weak market for home loans, and that weakness could feed back to hurt Freddie as well.

That is because its declining participation in buying home loans may trigger a loss of confidence among investors, leading to a broader selloff of mortgage investments, freezing the market.

Fannie also said it is slowing its purchases of mortgage-related securities.