De Bruyne hit out at Belgium coach Roberto Martinez's tactics for their 3-3 draw with friendly opponents Mexico.
"For me, these are matters that have to be arranged internally," Ciman said of De Bruyne's outburst. "We played a bad game against Mexico and immediately there is panic.
"But if we had won 3-0 and if Kevin had said that it was tactically not good, then that would never have received such a response.
"How it came to such statements? That's just Kevin. He always says what he thinks. At the European Championships it was just the same. But one must stop thinking that there is discord in the dressing room. There is no problem. We are a group of friends and everything goes as it should. Everyone has his character, but there is no question of egos being too big."