Ivory Coast international Toure left the Gunners to join Manchester City last summer after his relationship with Gallas deteriorated to the point where the two players were no longer on speaking terms.
Toure accepts someone had to move on and believes Gunners manager Arsene Wenger understood his decision to quit the club for City.
"Gallas and me misunderstood each other at certain times," said Toure ahead of his return to Arsenal with City on Saturday.
"In the end, one of us had to leave and it was me. I wanted to go.
"As a player I had great respect for him because he was older than me and, in Africa, when someone is older than you, you have to respect them. But I think sometimes he took advantage of that in some ways.
"It reached a point where me and Gallas didn't talk to each other at all.
"Arsene Wenger understood my position and I have huge respect for him. He realised that the two of us couldn't stay together.
"One of us had to go. You can't play two central defenders who don't communicate.
"I didn't want to make trouble for Arsenal because they had given me my chance in English football and I really enjoyed most of my time there.
"I didn't want to put the team in a difficult position, so I was the one who said, 'I want to leave'.
"I was with Arsenal for six years, but the last two years there were difficult and I had problems with a few people.
"I was not feeling happy in the team and I was looking for a new challenge somewhere else. It was the right thing for me and Arsenal."