Officers of the National Theatre heatedly denied yesterday that they have dropped their objections to a plan by the National Press Club to rebuild the downtown block where the press club and theater are located.

Despite the press club's decision Monday to include a new 1,500 seat theater in the project it wants to build in partnership with Atlanta-architect John Portman, "the National Theatre cannot endorse the Portman/press Club proposal unless to w major obstacles can be overcome," theater spokesman said.

Those obstacles, the theater said, are where and how to relocate the theater during the four years between the demolition of the present therater and completion of a new one, and how to pay for a new theater.

The Press Club and Portman are among three rival developers seeking designation by the Pennsylvania Avenue Development Corp. to rebuild the block bounded by 13th and 14th, E and F Streets NW. The PADC's board of directors meets today and tomorrow to choose a developer for the project.

Proposals made by the John Akridge Co. and Quandrangle Development Corp. in parternership with Marriott Corp. call for either leaving the theater in its present building facing F Street, NW., or building a new theater for the National.

The theater's board expressed a "strong preference" for the Akridge proposal, ranking the Quadrangle plan second.

After months of confrontation and many meetings between theater and press club officials, the club announced it had agreed to add a theater to its project. Press Club president Frank Aukofer said the action removed the theater dispute as an obstacle to the club's plans.

The National would have to pay about $7 million for the theater in the Portman project, but the press club would contribute $1.5 million in cash and Aukofer estimated the theater would have to raise only $1 million more.

But a statement prepared yesterday by National Theatre treasurer Gerson Nordinger called that estimate "an optimistic improbability" and said the press club's plans were "predicated largely upon doubtful sources of financial support."

Aukofer said the theater board "is taking the same position they took 13 months ago and that has not changed one whit despite six proposals we have given them."

He said the press club has tried repeatedly to compromise with the theater and noted that the financial plan for incorporating the theater into the press club project was based on a fund raising plan suggested by Roger Stevens, director of the Kennedy Center, which manages the theater.