The Trib New York Inc., parent company for a new morning newspaper scheduled to begin publication here this fall, filed suit today against The New York Times and two other firms, charging a conspiracy to prevent the Trib from publishing.

The antitrust suit against the New York Times Co., the I.H.T. Corp., and International Herald Tribune, S.A., alleges the defendants "are seeking to restrain trade and attempting to monopolize the distinct geographic area of the New York City metropolitan area" for publication of morning daily newspapers.

It charges The New York Times is intimidating potential advertisers in the new newspaper and has deliberately suppressed publishing any news about the Trib in its own publication.

Filed in federal court in Manhattan, the suit asks for injunctive relief and treble damages of $7.5 million under the Sherman and Clayton Acts.

At the same time, Trib New York, in a counterclaim, denied that its use of the name "The Trib" for the planned newspaper infringes on the trademark held by I.H.T. Corp. which filed a suit charging such infringement on Aug. 24.

The Iht. corp. is the successor to the New York Herald Tribune, which ceased publication in 1966, and is a 37 per cent owner of the International Herald Tribune, published in Paris. The New York Times owns 33 per cent of the International Herald Tribune and the Washington Post Co. owns the remaining 30 per cent.

The I.H.T. corp. is the successor to "Trib" is an abbreviation widely used for the International Herald Tribune and that its use for a new paper would be "a fraud and deception upon the public."

Today the company declined to comment until it had a chance to look at the suit filed by the Trip.

W. Barry McCarthy, a spokesman for the New York Times, said it had not yet been served with legal papers in the suit but had only seen a press release distributed at a news conference held today by Leonard Saffir, editor-in -chief of the new publications, at the Trib's still unfinished newsroom.

"Based on that publicity release," McCarthy said, "we're puzzled. The Times company has done nothing to obstruct publications of the new tabloid newspaper. And while we are one-third owners of the International Herald Tribune, the action to prevent the use of the name. The Trib, was taken not by us but by the owners of the trademark, the successors to the defunct New York Herald Tribune."

McCarthy said he was "unaware" of any suppression of stories by Times staffers about the Trib, an allegation Saffir made at his press conference.

The suit, meanwhile, charges that the Times conspired with I.H.T. Corp. to bring the trademark infringement suit, and that the timing of the action was "in bad faith" since I.H.T. has known since early this year that the company intended to use the name for its newspaper.

"Nearly $2 million has been expended so far in connection with the publication of the Trib," Saffir said. "As out suit points out, they waited before filing their suit well beyond the point where we could change the name of out paper without incurring substantial hardship."

Saffir said the Trib will begin publishing sometime this fall, but refused to be pinned down more specifically.

A prototype of the paper, which will be tabloid in format and moderate-to-conservative in its political outlook, was distributed in June to advertisers. The chairman of the board of the new company is William E. Simon. Treasury Secretary in the Nixon and Ford administrations, and former U.S. Sen. James Buckley is also on the board. Saffir was previously a top aide to Buckley.

Evidence that The New York Times is harassing potential advertisers in the Trib consisted of two memos from The Times' advertising department. One dated June 13, 1977 asked members of the national sales staff to keep executives "posted on any news you pick up - especially from and about advertisers who plan to use" the Trib.

The suit says The Times "well knew" that inquiries to advertisers about whether they planned to buy advertising space in the Trib "would convey an implied threat," and was "intimidating and coercive."