Arbeloa, who himself is under fire with Real all but certain to finish without a trophy this term, said Mbappe had nothing to reproach himself about and that aside from scoring in both legs of the quarter-final, he had "given his all in defence."
Real lost 4-3 in a thrilling second-leg tussle with Bayern Munich - who progressed 6-4 on aggregate - with the Spanish side reduced to 10 men after Eduardo Camavinga was sent off in the 86th minute.
Bayern scored twice after the Frenchman's dismissal, which sparked the criticism of Mbappe.
Arbeloa, though, was having none of this at his eve-of-match press conference on Monday.
"I have nothing to reproach Kylian about," said Arbeloa, whose side host Alaves on Tuesday.
"He was at the top of his game, he scored in both legs and was a constant threat to their defence.
"He gave his all in defence, and he worked really hard.
"I was thoroughly satisfied with his performance in that match," added the 43-year-old.
Mbappe, who has scored 40 goals in all competitions in his second season in Spain, will have to wait another year to realise "his dream" of winning the Champions League.
It was the reason why he joined Madrid from French giants Paris Saint-Germain, who promptly rubbed salt into his wounds by winning European club football's most prized trophy last term.
Whether Arbeloa, who replaced Xabi Alonso earlier this season, is the man still in charge next term is in doubt - arch-rivals Barcelona lead Real by nine points in the race for the LaLiga crown with seven matches remaining.
However, he refused to comment on his future, aside from saying it was not in his hands, but remarked that there was no need for a "huge revolution" at Real in order to turn things round next campaign.