Saxo Bank analyst Christopher Dembik said French Economy Minister Arnaud Montebourg appeared to be getting his way in forcing GE to come up with a better offer, though he warned other potential bidders for French firms might be deterred by the government's tactics.
"It's a clever game of poker in the short run for Arnaud Montebourg, but that could have harmful consequences in the medium and long run, particularly in relation to Anglo-Saxon investors who are wary of state intervention in economic affairs," he said.
"It's not unlikely that investors will now think twice before showing interest in a French industrial jewel."
Read MoreFrench govt gets more time to weigh GE/Alstom deal
Shares in Alstom rose as much as 1.9 percent on hopes for progress towards a deal with GE. Alstom management and investors have welcomed the U.S. company's bid, saying it would give Alstom cash to pay its growing debts and the critical mass it lacked in a difficult global power market.
The chairman of Siemens France said on Tuesday the German group hoped to make a formal offer by June 16 to buy most of Alstom's power assets and in exchange give up its own trains business, but that it was still looking at the opportunities and risks of a tie-up.
Meanwhile GE has extended its offer until June 23 at the request of the French government. With Alstom, GE sees a chance to push on with a renewed focus on its engineering and industrial roots, expand its installed base of power turbines, and increase exposure to emerging markets.
"Jeff Immelt is showing how serious he is about the transaction. He's getting himself involved hands-on, playing a good political game ... whereas Siemens doesn't appear to be as serious about the deal," said Nomura analyst Daniel Cunliffe.
Read MoreSiemens ready to make play in Alstom sweepstakes
GE declined to comment on the pledge to create 1,000 jobs.
"We had a constructive discussion about the details of our proposed alliance with Alstom. We have made progress and look forward to the conclusion of this process in the next few weeks," a GE spokesman said in an emailed statement.
The French government is not only keen to preserve French jobs, but also the country's energy independence. Alstom is a supplier of turbines for nuclear plants worldwide, and Paris is concerned that a sale of its power arm could hurt France's position in the energy sector.
On Tuesday evening, Immelt told French lawmakers GE would make detailed commitments to increase jobs in France and was in "constructive" talks with the government to secure French access to Alstom's nuclear-related assets.
He also said GE was considering giving control of its rail signaling business to Alstom, addressing concerns that a straight sale of the power arm would weaken the French group by reducing it to its smaller rail business.
Alstom, which was bailed out by the state a decade ago, makes France's iconic TGV high-speed trains. This transport business accounts for under 30 percent of group revenue.
If GE handed over its high-margin rail signaling business to Alstom, that would boost Alstom Transport's revenue by about 20 percent and its earnings by about 50 percent, according to Nomura's Cunliffe.
"That makes it politically a bit more palatable, from a French standpoint. And that would give Alstom latitude to use its cash to go out and make other acquisitions," he said.
Read MoreQuelle horreur! France's political triple-threat
A spokeswoman for Alstom declined to comment beyond saying its board was studying in depth GE's offer.