Venditti scored the first ever international try at the Stadio Olimpico in the first-half as Tommaso Benvenuti also crossed to give Italy a shock 12-6 lead.
But they could only add three more points after the break as the Azzurri fell away, like they did against France, in the second half.
It did not help that scrum-half Tobias Botes missed two eminently kickable penalties after taking the kicking tee from Kris Burton.
But Venditti maintains individual errors are less important than maintaining their collective standards from the first whistle to the last.
"Hopefully we can sort out these little errors and take the match all the way to the death against Ireland," he said.
"I am sure Toby will make a strong come back as well. To come of the bench and have to immediately take a kick at goal from afar and on the angle isn't easy.
"The elements weren't helping either and poor guy he slipped too. It doesn't matter he'll be back."
"I was so happy to score in front of all those people at home and also because there was another try for Tommy straight after, which made me very happy again.
"The tries showed we are growing and I thought we would bring the game home but it didn't happen.
"There we were at half-time suddenly in front but in the second half we relinquished possession and England come at us with ball in hand."