A Toronto-based life insurance company has paid a record price of $1,256 per square foot for two parcels of land two blocks from the White House, paying a total of $7.5 million.

Manufacturer's Life Insurance Co.'s real estate subsidiary purchased the two parcels from brothers Theodore and James Pedas, owners of the Circle Theaters, who paid a total of $3.2 million for them in separate purchases in 1983 and 1984, according to Rufus S. Lusk and Son Inc., a real estate information service.

Until the Manufacturer's Life purchase, the record for D.C. property was $1,194 per square foot paid by the World Bank last year for the site of its new building, now under construction at 18th Street and Pennsylvania Avenue NW.

One of the record-setting priced lots is the former site of the Sans Souci restaurant, now a Riggs Bank branch. The Black Steer restaurant is located on the other site, both in the 700 block of 17th Street NW.

The insurance company paid $1.5 million for a lot between the two Pedas properties, where a McDonald's restaurant is located. That property was purchased from another owner for a considerably lower price of $492 a square foot. McDonald's held a long-term lease on the building, which was valid no matter who owns the property, and could have prevented Manufacturer's Life from tearing down the building, according to an industry source. Manufacturer's has negotiated a new lease with McDonald's for space in the office building the company plans to build on the site, the source said.

Jay Bright, senior representative in Manufacturer's Washington real estate office, said he does not know why the lot containing the McDonald's building cost less than the other two. His company expects the new office building to be substantially completed by mid-1987, Bright said.

A building at the prestigious location near the White House could command rents of $35 a square foot or more, one commercial leasing expert said.

The Canadian insurance company, which has had a real estate office here since 1978, has nearly completed its first construction project in Washington, a 240,000-square-foot office building at 1850 M St., Bright said. Nearly half of the building has been leased, with the biggest tenant, GTE Service Corp., occupying the top two floors, he said.

The firm's portfolio contains more than 16 million square feet of office, industrial and retail space in the United States and Canada, with much of its U.S. property located in Washington, southern California and Chicago, Bright said.