"I would have done the same thing Jimmie did," Earnhardt said Thursday at Texas Motor Speedway. "If I'm leading the race, I have to think about my team, my car and what I'm trying to do."
Earnhardt was involved in an accident during the race at Martinsville that caused him to spin sideways on the track, bringing out a yellow flag.
Johnson was leading the race when he approached Earnhardt's No. 88 Chevrolet. Johnson slowed down before moving over and driving past Earnhardt's car.
Some of Earnhardt's fans were furious at Johnson, many ripping him on Twitter for not allowing Earnhardt to get his car going again and stay one lap down. But Earnhardt pointed out that Johnson did what he had to do.
"Jimmie couldn't slow down," Earnhardt said. "He did, actually, try to slow down, but if he slowed down too much, the guys behind him have the right to take his position. I lost a position to Hamlin under caution at Phoenix, so I know all about it."
By NASCAR rules, a driver must maintain a reasonable pace under caution to hold his position.
"Jimmie saw I had two right-side flat tires," Earnhardt said. "If he stopped at all, the guys behind him would have passed him.
"He couldn't take that risk. He didn't do anything out of spite. We shouldn't have been back there in the first place and be in position to get run over. It was a bad day for us and got worse."
Earnhardt finished 24th, two laps down, while Johnson won at Martinsville for the eighth time.
"Jimmie didn't do anything that he wasn't supposed to be doing," Earnhardt said. "He's leading the race and he had a race to win."