"Football is never totally rational," said the UEFA president, rejecting the idea that there were 'big' teams and 'small' teams.
"Trying to give a rational explanation for results is never easy.
"We have to respect what happens on the pitch. There are always people who are happy and people who are unhappy.
"We talk about the small teams, but I don't think there are big teams and small teams in the Champions League, I don't like the term small teams."
The group stage ended on Wednesday with Dinamo Zagreb losing 7-1 at home to Olympique Lyon, a result which meant the French side pipped Ajax Amsterdam to qualify for the last sixteen.
UEFA issued a statement denying there had been irregular betting patterns on the game following media speculation of foul play, which drew an angry reaction from the Croatian champions.
Zagreb were also beaten 6-2 by Real Madrid on their way to losing all six games and conceding 22 goals.
They were the second team to concede seven goals in a group game this season following Belgian champions Genk, who were beaten 7-0 by Valencia and also lost 5-0 at Chelsea.
Spain's Villarreal and Romanian champions Otelul Galati were also out of their depth, losing all their games.
Group H, meanwhile, was settled with two rounds of matches left as AC Milan and Barcelona qualified at the expense of Viktoria Plzen and BATE Borisov.
Barcelona knocked nine goals past BATE in two games and also won 4-0 at Plzen.
"There are games where the goalkeeper has a bad day, where the defence has been reshuffled, or perhaps a team has already been eliminated by the last match and are totally unmotivated," said Platini.
"You can see it in a positive way or a negative way."
Platini was equally philosophical on the few shocks, which included APOEL Nicosia qualifying and Manchester United knocked out by FC Basel.
"You don't win a match in the Champions League because you are a big name. Nobody is entitled to win all the time, I always respect the clubs from Cyprus and Switzerland," said Platini.
"There are always newcomers and I'm not saying its a bad thing, nor a good thing."
