Major League Baseball said it found no violations by the Houston Astros with regard to alleged sign-stealing during the postseason.

"With respect to both incidents regarding a Houston Astros employee, security identified an issue, addressed it and turned the matter over to the Department of Investigations. A thorough investigation concluded that an Astros employee was monitoring the field to ensure that the opposing Club was not violating any rules," MLB said in a statement Wednesday.

"All Clubs remaining in the playoffs have been notified to refrain from these types of efforts and to direct complaints about any in-stadium rules violations to MLB staff for investigation and resolution. We consider the matter closed."

General manager Jeff Luhnow said the Astros have been proactive in policing other ballparks for "suspicious activity" and that the team has uncovered such incidents "multiple" times. Luhnow said the club will abide by MLB's guidelines and that any prior monitoring was done as protection.

"We were playing defense; we were not playing offense," Luhnow said before Wednesday's Game 4 of the American League Championship Series in Houston.

The investigation arose after an Astros employee appeared to be seen shooting video from the photographer's pit adjacent to the Boston Red Sox dugout during Game 1 of the ALCS at Fenway Park.

Asked if the matter was resolved to his satisfaction, Red Sox president of baseball operations Dave Dombrowski said the answer is "yes and no."

"Yes, I do not think the person in the camera well was stealing signs," Dombrowski said. "And so I understand that was resolved. No, in the sense that first of all, there was a violation. A person was in the credential box that shouldn't have been there. He wasn't supposed to be there. Secondly, I don't like the implication that the Boston Red Sox are doing anything illegal.

"So, I don't think the issue is actually closed from Major League Baseball from what I've been advised from the commissioner's office. So, there's a lot more steps that are attached to this. So yes, it's partially closed, but I don't think it's all the way closed."

Dombrowski said he was under the impression that MLB's statement on the matter "would be the end of it."

"But then when I heard the Astros made a comment ... I'm not going to bury that suspicion on our organization," he said.

Dombrowski later added, "Don't forget, they were the ones that created a false credential or asked for a credential for somebody that's not supposed to have one. The person is not an employee of the Houston Astros, and that person's not supposed to be in the camera box.

"It's just a bad thing to put it upon our lap."

Cleveland.com reported Tuesday night that the Cleveland Indians filed a complaint with MLB about the Astros trying to film their dugout during Game 3 of the AL Division Series, and The Associated Press reported Wednesday that a second man attempted access to the field photographer's pit next to the Indians dugout.

Yahoo Sports reported Tuesday that Oakland Athletics players in August believed members of the Astros were relaying stolen signs during games and the team called to have the incident investigated. MLB addressed only postseason incidents in its statement.

The use of electronic devices during games is expected to be a topic of a wider discussion at next month's general managers meetings.

Prior to the postseason, MLB said "a number of clubs" had called commissioner Rob Manfred to express concerns about video equipment being used to steal signs. To address those worries, the commissioner instituted a new prohibition on the use of certain in-stadium cameras, beefing up MLB security at games and monitoring video rooms.

"There's some unintended consequences that come with the advancement of technology," Astros manager A.J. Hinch said. "It's a leaguewide conversation that needs to happen in time. It's happening right now during a really important series, and I just think it's bigger than us. It's bigger than any team. It's bigger than any series. It needs to be corralled because of the state of the concern over it.

"The competitive edges nowadays are so narrow. You're trying to find everything you can. And whether that's pitch tipping, pitch sequencing, changing your signs, changing your location of your defenders -- this is a bigger topic that's going to take a lot more time than an overnight story and concern and people's curiosities."

The Red Sox were fined last season by MLB for using an Apple Watch to try to steal signs from the rival New York Yankees.

The Associated Press contributed to this report.