Donis was also ecstatic about the way Al Hilal bounced back in the second leg after losing 1-0 in the first leg on May 19.
"I’m really proud of my players as the team achieved a big target for this season," Donis told reporters after the match. "The team showed great solidarity tonight as we were one unit and achieved the result that we were looking for."
Forward Yousef Al Salem opened the scoring for Al Hilal in the 29th minute before midfielder Mohammad Shalhoub converted a penalty in the 57th minute to make it 2-0.
Persepolis' dreams of reaching the quarter-finals were then extinguished when substitute Abdulaziz Al Dawsari scored in the 91st minute.
With so much on the line heading into the match, Donis revealed that he told his players to "play with good concentration".
"We asked the players to play with good concentration and things became easier after we scored the second goal," he said. "We showed great determination to make a good comeback after the defeat in the first leg and the performance was great.
"The players had a difficult season as we lost two finals which made things hard for them.
"Therefore, we asked them not to go forward without any concentration and we approached the match very well which helped us to win tonight."