The Red Sox go to Cleveland on Friday to play their final three games. Ortiz, who turns 40 next month, started two of the four games at Yankee Stadium.
"Some general soreness, the body is tired," said Lovullo. "He's had a really, really good season. And I don't want to put him in a situation where he's going to run up against an injury, out of fairness to him."
"I've been saying all along, he's played through days off, he played through a lot of days off in that little run that he was on," said Lovullo. "Chasing 500 home runs was bigger than any day off for me and I just wanted to make sure the medical team would sign off on it, David wanted to play, and just kept playing him through those days. So he deserves this time down."
If Ortiz does play against the Indians, he will probably won't participate in full games.
"I think if he plays again, it will follow that same pattern. I think that's fair to him, get him off of his feet," Lovullo said. "He wants to play. He asked to play in these games because he wants to make it as hard as he possibly can on a team that's looking to clinch and go to the playoffs. He wants his younger teammates to see that he's playing through tough conditions and his body is not perfect.
"It's been a long season. There's not one thing that's wrong with him that's holding him out of the lineup. Overall, he's just tired. And then he wants to win games because he likes to win games. He wants to contribute."
Ortiz was hitting .272 with 36 homers, 105 RBIs and a .905 OPS entering Thursday.
Ian Browne is a reporter for MLB.com. Read his blog, Brownie Points, follow him on Twitter @IanMBrowne and listen to his podcast. This story was not subject to the approval of Major League Baseball or its clubs.