U.S. District Judge Norma Johnson yesterday turned down a bid by stockholders to bar Computer Network Corp. from aquiring another firm in the near future.

The ban had been sought by John Spohler and Hugh Aiken, major Comnet stockholders who have been very critical of its management. Spohler said Johnson's refusal to grant a temporary restraining order to forbid an acquisition would be appealed.

Spohler and Aiken had requested the court order against a new acquisition because they believed that the computer processing company was getting ready to buy another company through the issuance of new stock. They said that such a move could dilute the company's stock and thereby make it harder for shareholders to challenge management in the annual meeting later this summer.

In a document filed with the Securities and Exchange Commission yesterday, Spohler said the firm he believed Comnet was getting ready to buy is a subsidiary of Dart Drug Corp. He said "a reliable source" had told him that the acquisition "was in the final stage" and would be achieved through issuance of Comnet stock.

Comnet's chairman, Lee Johnson, would not comment on Spohler's statement. Although Johnson had acknowledged earlier that Comnet is looking for companies to buy, he said "it would be improper for me to identify any company . . . "

Also refusing to comment were Comnet's lawyers, who also serve as Dart's counsel, Spohler pointed out in his SEC filing. Robert B. Hirsh is an officer of Dart and, as a senior partner of Arent Fox Kintner, Plotkin & Kahn, is also Dart's and Comnet's attorney.

Spohler has accused Comnet management of taking actions that would enrich the top officers at the expense of the shareholders.