The Justice Department said yesterday it plans to go ahead with its antitrust suit against Las Vegas financier Kirk Kerkorian despite the refusal of a federal judge to block his efforts to acquire 25.5 percent of Cloumbia pictures.

"We're going to push for a trial as soon as possible," said Barbara Reeves, who heads the department's Antitrust Division in Los Angeles.

Kerkorian personally and through his wholly owned venture capital firm, Tracinda Investment Corp., owns 48 percent of Metro-Goldwyn-Mayer Inc.

Tracinda acquired 5.5 percent of Columbia last fall for $9.7 million. The 61-year-old Kerkorian recently made a tender offer to acquire another 20 percent of Columbia.

With the tender expiring Tuesday, Justice on Monday asked U.S. District Judge A. Andrew Hauk to restrain temporarily Kerkorian from completing the tender.

Justice argued that the proposed acquisition by Kerkorian would violate Section 7 of the Clayton Act by reducing competition in production and distribution of motion picutres.

"Actual and potential competition between MGM and Columbia will be substantially lessened," the Justice suit alleged.

But Judge Hauk refused to halt the tender offer, because, he said, it would deny Columbia shareholders the opportunity to make a substantial profit on shares they tendered.

Kerkorian's offer of $24 per share of Columbia is about $2 above the price quoted for the company's common stock on the New York Stock Exchange.

A spokesman said last night that Kerkorian's tender offer was slightly oversubscribed but that he won't go beyond the amount set earlier.

Reeves said Kerkorian's attorneys are seeking to settle the action by making certain promises about what the financier will do with his stock.

Stephen Silbert, a Kerkorian attorney, said last night: "We will e glad to sit down with (Justice attorneys) if they are interested in settling this matter."

Kerkorian already has signed an agreement with the present management of Columbia. He promised to support the management and to vote with it on corporate issues.

He also has asserted that his acquisition of the stock, making him Columbia's biggest single shareholder, was an investment only.

The Justice suit said eight major movie companies account for an average of 86.2 percent of the annual domestic film rentals. MGM and Columbia combined handle an average of 13.8 percent.

Besides movies, Justice said the combination could lssen competition in the production of television series, phonograph records and tapes, which both companies produce.

Most of MGM's revenues now come from its hotels in Las Vegas and Reno. Kerkorian, in arguing against the government, said MGM and Columbia are "no longer substantial competitors."