The center-back was called to the home of United midfielder Harry McGuire after receiving a bomb threat via email, and the Czech police were called.
McGuinness has been criticized by United fans and rivals this season for being "bad" and Ralf Rangnick and Gareth Southgate, 29, have been criticized for swearing while playing the game.
The Sun reported on Thursday that an email had been sent to Maguire stating that a bomb had been planted at his family home.
"In the last 24 hours, Harry has received a serious threat to his family home," a spokesman said. "He has reported the matter to the police who are investigating, and it is clear that the safety of his family and the people around him is Harry's number one priority.
"He will continue to prepare for this week's fixtures as usual and will not comment on details at this time."
McGuire and police understand that the threat was serious and are investigating the source of the email.
Cheshire Police have confirmed that a dog trained in explosives was not removed from their home to search the park and surrounding area during their investigation.