The coach is pleased with his team's performances in the International Champions Cup and says Mateo Kovacic will not start against the Giallorossi on Saturday
The Nerazzurri finished a massive 25 points behind Rudi Garcia's men last season in Serie A but only three places adrift of the Scudetto runners-up, securing a return to Europa League football in 2014-15.
Inter have picked up respectable results in their pre-season trip to USA, beating Real Madrid on penalties before losing to Manchester United on spot kicks after both International Champions Cup fixtures ended a tie.
"So far everything has worked well in the US," Mazzarri told Inter Channel. "Now we face Roma.
"It is worth a lot for us to beat Roma, but we must look beyond the result. They are a very strong side and we know it will be a good test, but this isn’t Serie A yet."
One player who has been absent during Inter's clashes in North America is Croatian midfielder Mateo Kovacic, who has been suffering from a calf problem, and Mazzarri confirmed that he will not start again on Saturday against the Giallorossi.
"We don’t want to lose Kovacic, so he’ll be on the bench and will possibly play a few minutes, but without running any risks," the former Napoli coach added. "I wanted to let him start this one, but in training I saw he’s still struggling a little.
"Everyone is motivated and I expect more confirmations of our form tomorrow. Inter must never settle for less than 100 per cent."
Inter's clash with Roma kicks off at 19:00CET on Saturday in Philadelphia.