The two teams face off this week, with 21th placed Rotherham hosting their 10th placed visitors.
Speaking at a press conference, Evans revealed he tried to sign the forward while he was at Watford.
He said: "We tried to sign Britt Assombalonga before Peterborough got him and now I wish we had!
"He's a goal threat, he's strong and quick. I have nothing but pure respect for Nottingham Forest. Stuart Pearce has an incredibly talented squad with great travelling support."
The striker signed for the Posh in 2013, putting together a terrific season which saw Forest shell out £5.5 million for his signature this summer.
He has been a huge success, scoring 12 goals this season. Rotherham alone have netted only 16 times.