Interior Secretary James Watt has assured Major Marion Barry that the District will get $1.5 million in federal funds to renovate the Capital Children's Museum and four recreation centers, despite the Reagan administration's freeze on park projects.

Watt told Barry in a meeting last week that the grants would not be affected by the freeze. The grants, part of the Urban Park and Recreation program, were approved last year or in January -- prior to Watt's February announcement that pending federal park grants were being rescinded or canceled, subject to approval of Congress.

Although the city's grants appeared to be unaffected because they had prior approval, District recreation department officials were concerned. The city already had appropriated the matching funds needed for several of the projects.

One grant will enable the Capital Children's Museum to renovate a wing to house a new exhibition on communications. The museum, established three years ago with a $1.7 million federal grant that enabled it to buy an entire city block behind Union Station, will receive $500,000-$350,000 in federal funds and a $150,000 matching grant from the Kresge Foundation.

The other grants will be used for general rehabilitation and expansion of four recreation centers:

The Greenleaf-Syphax Recreation Center, operated by the city's Department of Housing and Community Development. The center, at Delaware Avenue and M Street SW, would receive $1 million -- $700,000 in federal funds and $300,000 from the District.

The Parkview Recreation Center at Warder Street and Otis Place NW, operated by the city's Department of Recreation, which would receive a $150,000 grant.

Two Boys and Girls Clubs of Greater Washington -- the Jelleff branch, 3265 S St. NW, and the Eastern Branch, 261 17th St. SE. They are scheduled to receive a $350,000 federal grant and are trying to raise the necessary $150,000 in required matching funds.

The federal money comes from the Land and Water Conservation Fund, from which Congress has allocated more than $5 billion during the past 16 years to buy and develop parks across the nation. The money comes primarily from offshore gas and oil leases.

In February, Watt also announced he was ending any further purchases of park land with federal money from the conservation fund, an action subject to the approval of Congress.