Humza Yousaf has insisted he is "absolutely committed" to free university tuition for Scottish students despite calls for a rethink.
University of Edinburgh principal and vice-chancellor Sir Peter Mathieson said asking wealthier families to pay was "worthy of calm consideration".
He argued the move could prevent a brain drain from Scotland.
The first minister said said he was "very proud" of the SNP's opposition to tuition fees.
He also took aim at Sir Keir Starmer, who said Labour is "likely" to abandon its opposition to university tuition fees for students in England as it could not "ignore the current economic situation".
"It is a shame that we have had recently Keir Starmer say that he won't do the same for students in England," Mr Yousaf told BBC Scotland.
