The Bees striker earned his first call-up to Gareth Southgate's squad ahead of their most recent Nations League ties, but Toney watched both from the sidelines.
His club coach was empathetic but challenged his attacker to move on quickly and focus on Saturday's clash at Bournemouth.
"Obviously it was a big thing for Ivan to go into the England camp," said Frank.
"No matter if he didn't come on the pitch, it was still a big moment in his life and a big thing.
"Unfortunately he didn't come on the pitch. Of course he wanted to play. Of course I wanted him to play. The Brentford fans, all of us hoped that he would come on the pitch, but it's Gareth's decision and I know how it is to be a head coach.
"There are 1,000 things to consider. You need to think about what is best for the team and not an individual player. As far as I know, there were quite a few other players that didn't come on the pitch.
"From our perspective, and we only look from our side of the elephant, it's difficult to see the bigger perspective. Of course, we wanted him on the pitch, but it's Gareth's decision and he's done a very good job for England.
"The way to get success is to show resilience and come back from smaller setbacks. Ivan hoped to get on the pitch; we need to move forward and prove people wrong by performing well. Ivan has a strong mentality."
Frank will need to make do without club-record signing Keane Lewis-Potter this weekend who has picked up a "minor" ankle/foot injury.
Ethan Pinnock could return to Premier League action having missed the beginning of the season, but Frank stressed it would likely be in an emergency scenario only, while Christian Norgaard (Achilles) is still "weeks away" from a return.
Frank was quick to praise Saturday's opponents, who are undefeated since their 9-0 thumping at Liverpool in August and have no new injuries to report after the international break.
"After a game like Liverpool, either you fall apart or you stick together and show you are stronger," he added. "They have players that can hurt us. Dom Solanke is a very good striker and Ryan Christie has done well as well.
"It will be another big challenge. Since he's taken over, Gary O'Neil has done a very good job. He has two draws and a win on the results side and the performances have also been very solid. They have been difficult to play against."