Momsen plays Jenny on the series but has only appeared in a handful of episodes this season due to "creative reasons".
The actress's absence from the show is also thought to be partly due to her commitments with her band The Pretty Reckless.
Momsen has now told TV Guide that she will not be returning to Gossip Girl just yet.
"Not for a while," she said. "I'm touring this whole year and they've been so supportive of the band and allowing me to do it. You can't physically do both at the same time."
Momsen has previously been criticised for her behaviour on set, though co-star Connor Paolo recently claimed that the attacks are unfair.
Gossip Girl returns for a new episode on April 18 on The CW.