A federal judge temporarily blocked yesterday U. S. Steel's bid to acquire Marathon Oil.

U. S. District Judge Joseph Kinneary in Columbus, Ohio, issued a temporary restraining order preventing the steel company from proceeding with its approximately $6.2 billion takeover bid after Mobil challenged an agreement between U. S. Steel and Marathon. U. S. Steel's offer to pay $125 a share for 51 percent of Marathon's stock raised still another obstacle to Mobil's offer to buy the Ohio-based oil firm for $85 a share.

Mobil charged that two options granted U. S. Steel were illegal and that the agreement violated federal securities laws and Ohio laws governing corporations.

Kinneary blocked U. S. Steel from exercising the two options, one of which would allow U. S. Steel to acquire a major portion of Marathon's domestic reserves for $2.8 billion even if Mobil won control of Marathon. The reserves, Marathon's interest in the Yates field in Texas, are part of the smaller oil company's attraction to Mobil.

The other option gave U. S. Steel the right to purchase 10 million shares of Marathon Stock at $90 a share.

The restraining order also moved back to Dec. 8 the date by which shareholders must tender their shares to U. S. Steel to be sure of receiving at least a prorated share of the price.

The restraining order will stay in effect until Dec. 4, a day after a hearing is scheduled on a preliminary injunction.

In other developments, U. S. Steel has moved to increase its line of credit by another $2 billion, and Mobil confirmed that it has acquired nearly $15 million in U. S. Steel stock.