PC Simon Travell, dedicated football officer for Forest, said he would be would be speaking to West Yorkshire Police about the incident.
A twitter post, now deleted, appeared to show Grabban, who is a Muslim convert, wearing a suicide vest.
The account which posted the image has also now been deleted.
Grabban scrambled an equaliser in the 77th minute, with the game at Elland Road finishing 1-1.
PC Travell posted on Saturday evening: "I’ve been made aware of a Racist Tweet mentioning Lewis Grabban. I will be liaising with @LUFC_WYP (West Yorkshire Police's dedicated Leeds United team) to assist them where possible in their enquiries. Thank you once again. #KickItOut"
A post on Facebook also appeared to compare Grabban, 31, to a character from the film about would-be Islamist terrorists, Four Lions.
In April, footballers from across the country took part in a social media blackout due to the rise in racism.
At the time, Grabban tweeted: "#Enough. We are making a stand against racist abuse. We recognise that our platforms come with responsibility, and so we are using our voice to stand against racist abuse. Together, we are calling on social media platforms and footballing bodies to do more!"