Two of the nation's biggest retailers, Sears Roebuck and Co. and Montgomery Ward, said yesterday they plan to raise the minimum monthly payments due on their 44 million charge accounts, to comply with the Carter administration's latest inflation-fighting tactic.

The decision will mean bigger bills -- perhaps as soon as next month -- for many holders of the 26 million Sears credit cards and 18 million Ward's charge accounts.

Several more major credit card issuers are expected to take similiar steps today as lenders search for ways to meet the president's goal of curtailing consumer borrowing.

Raising monthly payments on revolving charge accounts, lowering the amount customers can borrow under personal credit lines and imposing new service charges on bank credit cards like Visa and MasterCard are the main steps creditors are contemplating.

Two big credit card companies, American Express and Diners Club, however, said they will seek exemptions from credit controls so their customers can continue to use their cards without restrictions.

American Express and Diners executives contended yesterday that the two cards are used primarily for business travel and entertainment, and therefore ought not be covered by controls meant to limit consumer credit. Both claimed also that they are not extending credit to consumers, because under their rules the entire balance of an account is due each month.

The White House and Federal Reserve Board have given no indication so far that they will exempt any credit cards from their efforts to curtail borrowing.

The inflation-fighting strategy announced Friday in effect puts a cap on the amount of consumer credit that can be extended without penalty by banks, stores and other lenders.

The cap is the amount of money owed by all charge customers as of March 14. If the companies increase their lending beyond the March 14 level, they must put 15 percent of the excess in a non-interest-bearing bank account. This adds to their costs. The money stays in the bank until the account is paid off or the lender's total amount outstanding falls back below the March 14 level.

The Federal Reserve offered no details of how lenders are supposed to comply with the edict and executives scrambled yesterday to try to figure out how to keep credit balances from growing.

Sears, which has more charge accounts than any other retailer, took what was regarded as the most simple solution -- make customers pay their bills faster.

Sears executives said the company has not yet decided how much it will raise the minimum monthly payments on its accounts. Sears' customers now must pay $8 a month on an account with a balance of up to $160, 5 percent of the unpaid balance between $160 and $260 and between 4 and 5 percent of larger accounts.

Montgomery Ward officials said that company will also increase its minimum monthly payment and is considering increasing the interest it charges on accounts, where that is permitted by state law.

In the District of Columbia, Maryland and Virginia, most credit companies cannot raise their interest rates because they are already charging the maximum permitted by local usury laws.

Ward's executive vice president for finance, G. R. Worley, said the company plans to ask the Federal Reserve Board to waive all state usury ceilings, so lenders can charge any interest rate they want.

The Fed has already set aside all state ceilings on home mortgage interest charges and has the authority to extend that action to other lending.

Rather than raise interest charges, other creditors are planning to put on new service charges or raise their annual membership fees.

"Obviously we are raising our fees -- the amount is being discussed now," said Michael Monroe of American Express. American Express now charges its 8 million cardholders $25 a year for use of the card.

The Visa card, which is given free to customers by most banks that issue it, is considering adding a membership fee. "The new controls will necessitate increases in the price of bank cards if the service is to continue to be available," said Dee. W. Hook, president of Visa. Some state laws will have to be changed before banks can charge for their credit cards.

Because of the uncertainties over how the consumer credit limits will work, many lenders put their credit operations on hold yesterday.

"We're not doing anything. We're not raising limits [on credit lines] or issuing new cards until we know what this means," said Rich Dautry, assistant vice president of First & Merchants National Bank.

Other merchants, banks and lenders said they will need guidance from federal officials before they can decide what to do about limiting credit. Federal Reserve Board officials said they expect to meet later this week with lenders.

The broad authority granted to federal officials by the Credit Control Act of 1979 apparently makes it legally possible for lenders to unilaterally change the terms of charge accounts, forcing customers to pay bigger payments than they counted on when they opened the accounts.