The Scottish Labour leader said it did not surprise him that others in the party did not join his calls for Sir Keir to resign, which he said hurt him on a personal level.
Sarwar said there was “no point pretending there wasn’t personal pain, but I did what I did and I stand by it”.
He added: “People know what the tipping point was for me but what I’m relentlessly focused on is making sure that we change the first minister in this country because this election is about our schools, our hospitals, our local services.
“It’s about our towns, cities, villages and islands. It’s not about an endorsement of Keir Starmer or voting for who the prime minister is.
“It’s about rejecting 20 years of the SNP and getting change with Scottish Labour.”
The Faslane base, on the Gare Loch about 25 miles (40km) north-west of Glasgow, is the home of all the Royal Navy’s nuclear submarines.
This includes the UK’s four Vanguard-class ballistic missile submarines which carry Trident nuclear missiles.