"Notwithstanding Heidi's request, if granted, it could in effect move the children away from me and their home here in Los Angeles to Germany for what could be an indefinite period of time," he explained in the documents.
"Given the uncertainty of the impact of COVID-19 on this country's and Germany's travel restrictions, which could change at any time and prevent the children from leaving Germany or from entering the United States."
Klum has also claimed that her ex-husband "doesn't see their children regularly anyway," but seal explained that it "isn't for lack of trying."
"Unfortunately, when I ask Heidi for more time to see the children, Heidi often makes it unnecessarily difficult by alleging that she and the children are 'busy' on particular days, that the children are ill, or that they simply cannot see me," Seal claims.
"As such, I am often forced to see the children on Heidi's schedule and when it is convenient for her, which has significantly decreased my custodial time. Nevertheless, I make it a point to spend as much time with the children as possible and to make myself accessible to the children."
He added: "I believe Heidi's (request) is a disguised attempt to move away with our children to Germany," citing a March 17, 2020, email she sent explaining her desire to relocate with the kids."
He also claims Klum has "previously expressed to me her concerns that the US would turn into a 'police state' in the face of social unrest."
Klum and Seal share four children: Henry, 14, Johan, 13, and Lou, 10, plus Klum's daughter Leni, 16, whose biological father is Flavio Briatore.
Klum and Seal's divorce was finalised in October 2014 after nine years of marriage. She secretly married Tom Kaulitz last year.