Media playback is not supported on this device
Keetels, a member of the victorious 2014 World Cup team, fired low past Maddie Hinch in the fourth quarter after two shots had been blocked.
England won several penalty corners, but were frustrated by a resilient Dutch defence.
Alex Danson did go close though with a shot saved by keeper Anne Veenendaal.
Danson's team-mate Sophie Bray also went agonisingly close to scoring as she failed to convert Zoe Shipperley' low driven pass.
Keetels said: "It was amazing. I'm so happy. The English attacked and defended well.
"We are enjoying the pressure. The crowd is all orange so it feels like an extra player on the field."
The home nation will play neighbours Belgium in Saturday's final. England will take on Germany for the bronze medal prior to that match.
England play Netherlands again, this time in the men's semi-finals on Friday (19:00 BST).

Djokovic beat Japan's Kei Nishikori in his quarter-final match in straight sets, 6-3, 6-2, 6-4.
He admitted after the match that he hadn't practiced before his match because he'd played five sets against Gilles Simon.
"I was determined, focused. In important points and moments I managed to stay composed and make him play an extra shot," he said.

He faces charges including hostage-taking, kidnapping and conspiring to use a weapon of mass destruction.
Belmokhtar remains at large and the US is offering a $5m (Â£3.2m) reward for information leading to his arrest.
Three US citizens were among at least 37 hostages killed when Algerian troops stormed the Tigantourine plant.
Days earlier, gunmen had seized local and foreign workers at the complex.
"Belmokhtar brought terror and blood to these innocent people and now we intend to bring Belmokhtar to justice," said Preet Bharara, US attorney for the Southern District of New York, in a statement.
Profile: Al-Qaeda in North Africa
The charges unveiled on Friday said Belmokhtar had appeared in an online video the day after the siege ended, claiming he had carried out the attack on behalf of al-Qaeda.
George Venizelos, head of the FBI's New York office, said the charges "describe a fanatical jihadist leading an extremist vanguard of an extremist ideology''.
Belmokhtar is a former leading figure in al-Qaeda in the Islamic Maghreb (AQIM) but is now believed to head a group of militants known variously as the Signed-in-Blood Battalion, the Masked Men Brigade and the Khaled Abu al-Abbas Brigade.
He was designated a foreign terrorist by the US Treasury Department in 2003.
The hostage crisis began on 16 January when militants attacked two buses carrying foreign workers from the Tigantourine gas facility near In Amenas in eastern Algeria.
The militants took foreign workers hostage at the gas complex, which was quickly surrounded by the Algerian army. Special forces stormed the living area on 19 January and the gas treatment plant two days later.
At least 29 militants also died in the shoot-out.

The search to find someone for the bellowing role in Swadlincote, Derbyshire first began in April.
But one applicant withdrew ahead of the second round of auditions last Friday and the second was unable to attend.
The council said it has not given up just yet and are "optimistic" of finding someone eventually.
Kate Allies, from the recruiting team at South Derbyshire District Council, said she was "surprised" so few people applied but said: "We are not giving up trying to find a town crier.
"It has to be the right candidate because this is very important for Swadlincote."
The role was introduced after residents asked for a town crier as part of a survey on what they wanted in their area.
It would be paid for with some of the Â£40,000 Heritage Lottery Funding that was given to the Swadlincote Townscape Heritage Scheme to revive the town.
Ms Allies said they were trying to rearrange a new trial with the one applicant left before re-advertising the vacancy for a third time.
"It will definitely happen," she said.
"People have asked for it and there has been a lot of interest for it, we just need the right candidate."
England's hopes of defending their EuroHockey title were thwarted at the semi-final stage as Marloes Keetels' strike sent hosts Netherlands through.
[NEXT_CONCEPT]
World number one Novak Djokovic will play Roger Federer in the men's semi-final at the Australian Open.
[NEXT_CONCEPT]
US prosecutors have charged militant Islamist leader Mokhtar Belmokhtar over a deadly siege at an Algerian gas plant in January.
[NEXT_CONCEPT]
A town has struggled to find its first town crier after only two people applied for the job and then failed to turn up to auditions.