Investigators from the joint Organised Crime Partnership detained individuals aged 42, 29, 26 and 25 on Wednesday at locations in central Glasgow, Anniesland and Parkhead.
At two properties in Anniesland and Harthill an estimated 500 cannabis plants were recovered.
The four remain in custody.
NCA Operations Manager Rob Miles said:
“Working with colleagues from Police Scotland as part of the Organised Crime Partnership we are determined to do all we can to protect our communities and disrupt the networks involved in drug supply across Scotland.”
Detective Inspector Tom Gillan of the Organised Crime Partnership (Scotland) said:
“Working in partnership Police Scotland is determined to ensure the activities of organised crime groups are frustrated and disrupted as part of our commitment to the country’s serious organised crime strategy.”