Strauss, the England and Wales Cricket Board's director of cricket, told Pietersen in May that he would not be considered for an international recall.
"I think that clarity has helped," Strauss said.
England won the Ashes 3-2 but trail 2-0 in the one-day series before Tuesday's third ODI at Old Trafford (14:00 BST).
Pietersen, 35, who was initially sacked after the 5-0 whitewash in the 2013-14 Ashes series, remains England's record run-scorer in all formats.
But Strauss believes the team has "moved on".
He added: "The danger at that time was that particular issue would overshadow everything that happened on the pitch over the course of the summer.
"What I was trying to do was provide clarity going forward so everyone knew where they stood.
