The Nerazzurri must now overturn a 3-0 deficit at the San Siro if they are to progress to the quarter-finals of the Europa League.
"I think Tottenham were honestly superior tonight in different ways, but we suffered more than anything on a physical level," Football Italia quotes Stramaccioni as saying.
"The real regret is we didn't make the most of those two great scoring opportunities, as we could've kept the qualification a lot more open than it is now.
"Tottenham confirmed their strong current form, now we must turn over a new leaf and look ahead to Bologna."
The second leg takes place next Thursday.