"We will not forget the role Lady Veronica played at the time of the Homeland War, when she organised humanitarian aid deliveries to Croatia. Together with her husband, she was among the friends who came to our aid when we needed it most," Mesic said in a telegram.
Veronica Maclean, the widow of British diplomat Fitzroy Maclean, died on Friday at the age of 84.
Mesic met Mrs Maclean in London during his official visit to Great Britain in late 2001 and posthumously decorated her husband for his contribution to the struggle of the Croatian people against Nazism and Fascism in the Second World War.
Mr Maclean led a British military mission with the Yugoslav Partisan resistance movement in the Second World War and later became a close friend of Yugoslav communist leader Josip Broz Tito.
Mrs Maclean frequently visited Croatia, particularly the southern island of Korcula where she owned a house.