The Yamaha rider battled with the defending champion throughout the race at Mugello but was helpless to stop Marquez overtaking him on the long straights.
That meant Repsol Honda's Marquez was able to claim another win - he has triumphed in all six races this season - as his outstanding form continued.
"The only thing (different) was probably the top speed," Lorenzo told Autosport.
"Maybe with higher top speed I could've got away. I think I was a little bit faster than Marc this time, but he could follow me when I was pushing.
"When he passed me, it seemed he was a little bit slower. But on top speed he gained a lot of metres."
However, Lorenzo is happy with the improvements being made at Yamaha this season and hopes to stop Marquez making it seven straight wins in Barcelona later this month.
"We've made some modifications to the bike that improved the braking so much," he added.
"I couldn't fight with Marc in all the braking points, but maybe 60 per cent of them - much more than last year.
"Last year it was very difficult for me to fight with Marc. I couldn't pass him under braking, but had more corner speed.
"We still have more margin to improve, but if we can do it, we can fight with him on the brakes."