President Trump on Friday grudgingly signed the $1.3 trillion omnibus spending bill passed by Congress despite his concerns over the price tag and immigration issues — including the lack of full funding for his long-promised border wall in exchange for a deal on Dreamers.

“They created a series of documents that nobody was able to read,” he complained about the 2,000-plus page bill — which Congress passed before most members had time to read it.

But, he added, the omnibus bill was important because it boosted defense spending by $60 billion over last year, including pay hikes for the troops.

“As a matter of national security I’ll sign this omnibus budget bill,” he said, but warned that he would never sign such a hastily prepared bill again.

“There are a lot of things I’m unhappy about in this bill. There are a lot of things we shouldn’t have had in this bill but we were, in a sense, forced [to] if we want to build our military, we were forced to have,” he added during an event in the Diplomatic Reception Room at the White House.

The commander-in-chief said the hikes in defense spending will allow the military to obtain more state-of-the-art aircraft, submarines and missile defense systems.

“We have to have, by far, the strongest military in the world. And this will be the strongest military we ever had.

The president also demanded an end to the filibuster rule and for line item budget veto power from Congress.

And despite his complaints, he thanked Republicans in Congress for his efforts preparing the bill.

Trump had earlier Friday threatened to veto the bill — and was reportedly fuming all morning about details in the bill he didn’t like.

“I am considering a VETO of the Omnibus Spending Bill based on the fact that the 800,000 plus DACA recipients have been totally abandoned by the Democrats (not even mentioned in Bill) and the BORDER WALL, which is desperately needed for our National Defense, is not fully funded,” Trump wrote on Twitter.

Congress passed the massive spending bill just after midnight Friday — after the Trump administration initially said he would sign it.

Mick Mulvaney, director of the Office of Management and Budget, told reporters Thursday that the bill “funds his (Trump’s) priorities.”

“Let’s cut right to the chase: Is the president going to sign the bill? The answer is yes,” he said, CNN reported.

“Is it perfect? No,” Mulvaney added. “Is it exactly what we asked for in the budget? No. Were we ever going to get that? No. That is not how the process works.”

The Senate voted narrowly to avert a government shutdown by passing the spending bill, which increases military and domestic spending and strengthens background checks for gun purchasers. The House approved the bill a day earlier.

Trump wanted billions more for the wall in exchange for protection for Dreamers, illegal immigrants brought here as children who were protected from deportation by the Deferred Action for Childhood Arrivals program.