Andy Murray says he does not know the extent of his abdominal injury but hopes the setback does not derail his grass-court season.
Murray, due to play at Queen's this week before Wimbledon in a fortnight, received medical treatment twice and was in visible discomfort when serving.
"Hopefully it's all right," he said.
"Obviously I've played a lot of matches. This is the most matches I've played in two weeks since probably 2016. That's a really long time.
"It's probably normal that I would feel some stuff in my body but I don't really know the severity of it.
"I won't know anything until I get it checked out. It's tough to say anything about the next weeks."
Two-time Wimbledon champion Murray, 35, had been bidding for a first grass-court singles title in six years but was beaten 6-4 5-7 6-3 by Italian world number 10 Berrettini.
Before the five matches he played in Germany this week, the 35-year-old Scot had played four times in Surbiton the previous week on his way to the semi-finals of the Challenger event there.
Murray, whose career was nearly ended when he needed a hip resurfacing operation three and a half years ago, had been moving freely in Sunday's final before having to call for the physio after he was broken in the opening game of the deciding set.
He then had more treatment while serving at 30-0 at 2-4 and while he managed to hold serve in that game, he seemed to be in discomfort for the rest of the match and was broken in the final game.
"I got some pain in my ab when I was serving. Not something I've had before," the three-time Grand Slam champion said.
It was a disappointing end to what had been one of the best tournaments he has had since his comeback from hip surgery.
His run will lift him back into the world's top 50 for the first time since 2018 when the new rankings are published on Monday.
"Sorry I couldn't get over the line today, but there's been a lot of progress the last few weeks. I'm looking forward to what the future has to hold," he said in his on-court interview.
"I'm feeling a lot better about my game. Hopefully my body can hold up a little while longer so I can keep playing matches like this."
The Cinch Championships at Queen's Club in London start on Monday, with Wimbledon beginning on 27 June.