The Ferrari driver suffered irreparable damage to his car after running over a loose water valve cover during the early stages of opening practice, an incident which resulted in the session being cancelled.
Ferrari were forced to change Sainz’s power unit, chassis and survival cell, triggering a minimum 10-place grid drop for the Spaniard.
The Italian team requested the sanction to be waived but saw their efforts to be granted an exemption rejected despite the stewards admitting they tried to avoid penalising Sainz.
An unhappy Sainz made his feelings about the situation clear after a heavily-delayed second practice.
“I’m okay. I had a pretty big hit on my back and on my neck after the incident that you guys all saw,” said Sainz, who finished second behind Ferrari teammate Charles Leclerc in FP2.
“Unfortunately, obviously the chassis, the power unit, the battery, even my seat was damaged after the incident.”
He added: “Unfortunately, as the session finished, the team communicated to me that I was taking a 10-place grid penalty for something that I have no fault and the team has no fault.
“Obviously this has changed completely my mindset and obviously my opinion on the weekend and how the weekend is going to go from now on. You can obviously imagine how disappointed I am, in disbelief with the situation and you will not see me very happy this weekend.”
Sainz believes the penalty highlights where F1 can be improved.
“What happened today for me is a very clear example of how the sport can be improved in so many ways,” he said.
“The FIA, teams, rules that – this could clearly be applied as force majeure for me not to take a penalty, but some way there’s always people, always ways to make this situation worse for an individual.
“And I think in this case it’s my turn to pay the price.”
Ferrari boss Fred Vasseur had earlier fumed at the severe damage sustained to Sainz’s car, branding F1 as “unacceptable”.
Despite his disappointment at his penalty, Sainz thanked the “heroic effort” of his team to get his car fixed and ready in time to take part in FP2.
“It involved a huge effort from all the mechanics and the team to put together a completely brand new car for FP2 that allowed me to complete the session,” he said.
“It was, in my opinion, a heroic effort by the team and the mechanics and I could take [part] in the session. We managed to do it, recover the time and focus on tomorrow.”