Secretary of Education Lauro F. Cavazos appears to be bracing for criticism over cuts in school support when President Reagan presents Congress with his final budget next month.

Cavazos, who promised at his confirmation hearing to fight for "the best funding possible," now says only "I did the best I could" in arguing for education money.He did not disclose any figures for his department, but Office of Management and Budget officials have said they cut $35 billion across the government to hold the deficit to $100 billion in Reagan's lame-duck blueprint for fiscal year 1990.

Cavazos, the junior member of Reagan's Cabinet and one of the holdovers who will serve in President-elect Bush's Cabinet, was asked in an interview with The Associated Press if the budget will reflect his principles.

The former Texas Tech University president hesitated then replied, "I really don't know how to answer that. And I'm honest about that. I did the best I could. That's all I can tell you. . . . That's going to be the budget and that's the one that I will defend."

Cavazos said it is too soon to talk about what shape the budget will take in the Bush administration, or what programs he will launch to combat such problems as illiteracy and the steep dropout rate.

However, Bush did make several detailed campaign proposals to boost education spending, including a new $500 million "Merit Schools" program to help the disadvantaged and $50 million for magnet schools.