The king visited Malaysia on February 26 as part of a month-long Asia tour.
"They were planning to attack Arab royalties during their visit to Kuala Lumpur. We got them in the nick of time," Inspector General of Police Khalid Abu Bakar told reporters.
Two of the seven were planning to launch a large-scale attack using a "vehicle-borne improvised explosive device".
On Sunday, Malaysia said it had arrested one Malaysian and six foreigners - one Indonesian, four Yemenis and one East Asian - between February 21 and 26 for suspected links to terrorist groups including ISIS.
Malaysia has arrested hundreds over the last few years for suspected links to terrorist groups.
A grenade attack on a bar on the outskirts of Kuala Lumpur in June last year wounded eight people. ISIS claimed responsibility for the attack.
Salman was in the capital Kuala Lumpur with a 600-strong delegation before leaving for Indonesia.
Saudi King Salman visit to Malaysia on Sunday was part of a multi-nation tour aimed at boosting economic ties with Asia.
(This story has not been edited by NDTV staff and is auto-generated from a syndicated feed.)