Greater Manchester Police said in a tweet on Saturday that two new people had been arrested after a raid on an address in Cheetham Hill.
"A controlled explosion took place to gain entry into the address," the tweet also said. "Two men - aged 22 and 20 - have been arrested on suspicion of offenses contrary to the terrorism act."
Televised images showed the aftermath of a raid on Brideoak Street in Cheetham Hill in northern Manchester.
Police said in a news conference on Friday that they had arrested a "large part of the network" behind the Manchester suicide bombing but that more arrests were likely.
The tweet on Saturday said "13 people in total have been arrested, of which two people have since been released without charge. A total of 11 men remain in custody for questioning."
A suicide bomber killed at least 22 people in a packed concert hall in Manchester, in what British Prime Minister Theresa May called a sickening act targeting children and young people.