Mitrovic was booked for his challenge on Idrissa Gueye and while VAR did review the incident, it did not alter the decision of referee John Brooks - something Lampard feels was a mistake.
"I thought it was a red card," the Everton manager said.
"I thought the parameters are what they are, about the ankle, a kind of stampy tackle.
"I think to be fair Mitrovic put his hand up straight away, we've all been there to a degree, so there's no shame, it's just a red card with the benefit of VAR.
"I was really surprised it didn't get given, really surprised."
Fulham were left to rue a host of missed opportunities after failing to find a breakthrough despite having 24 shots during the match, of which Mitrovic had 10.
The Cottagers went into the game having scored 22 goals this season - only Arsenal, Manchester City and Tottenham had found the net more times coming into the weekend - but they drew a rare blank against manager Marco Silva's former club.
Determined defending and solid goalkeeping from Jordan Pickford when called upon helped Everton follow up their 3-0 home win over Crystal Palace - which came after a run of three successive defeats - with a hard-fought point at Craven Cottage.
Lampard believes his side are showing a spirit that was lacking last season, when they were battling against relegation.
When asked about performances being improved this campaign, Lampard said: "How we set up (we have) a mindset of resilience that we didn't really have last year.
"We've gone on the road and played better than we have today, we played better at Leeds for instance and some games like that, but there is a different feel to it in terms of how we travel on the road."
Fulham boss Silva believes his side deserved all three points, saying they were the best team "by far".
"A very good performance from ourselves again," Silva said.
"We clearly deserved the three points, we were the best team on the pitch by far.
"It's not easy to do what we did this evening, against Everton, against a good side."
Silva felt his normally-clinical side created enough chances to have scored two or three goals against Everton and hopes that will continue to be the case going forward.
"This is the main thing for us. If you keep doing it this way, more goals will come because you are creating," he said.
"We are showing the desire, the quality to create chances."